Overview.bs

<pre class='metadata'>
Title: CSS Text Module Level 3
Shortname: css-text
Level: 3
Status: ED
Work Status: Refining
Group: csswg
ED: https://drafts.csswg.org/css-text-3/
TR: https://www.w3.org/TR/css-text-3/
Previous Version: https://www.w3.org/TR/2018/WD-css-text-3-20181206/
Previous Version: https://www.w3.org/TR/2018/WD-css-text-3-20180920/
Previous Version: https://www.w3.org/TR/2017/WD-css-text-3-20170822/
Previous Version: https://www.w3.org/TR/2013/WD-css-text-3-20131010/
Previous Version: https://www.w3.org/TR/2012/WD-css3-text-20121113/
Issue Tracking: Tracker http://www.w3.org/Style/CSS/Tracker/products/10
Test Suite: http://test.csswg.org/suites/css3-text/nightly-unstable/
Editor: Elika J. Etemad / fantasai, Invited Expert, http://fantasai.inkedblade.net/contact, w3cid 35400
Editor: Koji Ishii, Invited Expert, kojiishi@gluesoft.co.jp, w3cid 45369
Editor: Florian Rivoal, Invited Expert, https://florian.rivoal.net, w3cid 43241
Abstract: This CSS module defines properties for text manipulation and specifies their processing model. It covers line breaking, justification and alignment, white space handling, and text transformation.
At Risk: the ''full-width'' value of 'text-transform'
At Risk: the ''full-size-kana'' value of 'text-transform'
At Risk: the &lt;length> values of the 'tab-size' property
At Risk: the 'text-justify' property
At Risk: the percentage values of 'word-spacing'
At Risk: the 'hanging-punctuation' property
At Risk: the ''line-break/anywhere'' value of the 'line-break' property
Ignored Vars: letter-spacing
Status Text: This publication partially addresses the issues in the <a href="https://drafts.csswg.org/css-text-3/issues-lc-2013">disposition of comments</a> since the <a href="https://www.w3.org/TR/2013/WD-css-text-3-20131010/">October 2013 Last Call Working Draft</a>, and, while a marked improvement over the previous draft, is not considered to be entirely up-to-date at the time of publication. A completed dispostion of comments and corresponding draft will be published once the issues are fully addressed and reviewed by the CSSWG and Internationalization WG.
WPT Path Prefix: /css/css-text/
</pre>
<pre class=link-defaults>
spec:css-display-3; type:property; text:display
spec:css-fonts-4; type:property; text:font-feature-settings
</pre>

  <style type="text/css">
    img { vertical-align: middle; }
    span[lang] { font-size: 125%; line-height: 1; vertical-align: middle;}

    /* Bidi & spaces example */
    .egbidiwsaA,.egbidiwsbB,.egbidiwsaB,.egbidiwsbC
      { white-space:pre;font-size:80%;font-family:monospace; vertical-align:2px; margin:1px }
    .egbidiwsaA { background:lime;padding:2px; }
    .egbidiwsbB { border:2px solid blue }
    .egbidiwsaB { background:yellow;border:2px dotted white }
    .egbidiwsbC { border:2px dotted red }

	.hyphens-ex {
		border: thin solid black;
		display: inline-block;
		padding: 4pt;
	}

    /* Start Letter-spacing Tutorial */
    .ls-ex {
      font-size: 200%;
      margin-left: 1em;
      margin-right: 1em;
    }
    .ls-fixed-width {
      width: 10em;
    }
    .color-box { background: rgb(224, 203, 82); }
    .bad { color: red; }
    .good { color: green; }
    /* End Letter-spacing Tutorial */

    .char { border: 1px dotted gray; }
    .quarter { font-size: 25%; }
    tt[lang="ja"] { font-family: "MS Gothic", "Osaka", monospace }
    div.figure table {
      margin :auto;
    }
    .feedback {
      background: #FFEECC;
      border-color: orange;
    }
    .feedback:before {
      content: "Info Needed";
      color: #FF8800;
    }
    .data .no { color: red; }
    .data .ok { color: green; }
    .data th em { display: block; font-size: smaller; font-weight: normal; font-style: italic; }
  </style>

<h2 id="intro">
Introduction</h2>

  <p>This module describes the typesetting controls of CSS;
  that is, the features of CSS that control the translation of
  source text to formatted, line-wrapped text.
  Various CSS properties provide control over
  <a href="#transforming">case transformation</a>,
  <a href="#white-space">white space collapsing</a>,
  <a href="#white-space">text wrapping</a>,
  <a href="#line-breaking">line breaking rules</a>
  and <a href="#hyphenation">hyphenation</a>,
  <a href="#justification">alignment and justification</a>,
  <a href="#spacing">spacing</a>,
  and <a href="#edge-effects">indentation</a>.

  <div class="note">
    <p>Note: Font selection is covered in <a href="https://www.w3.org/TR/css-fonts-3/">CSS Fonts Level 3</a> [[CSS-FONTS-3]].

    <p>
    <span id="decoration"></span>
    <span id="text-decoration"></span>
    <span id="line-decoration"></span>
    <span id="text-decoration-line"></span>
    <span id="text-decoration-color"></span>
    <span id="text-decoration-style"></span>
    <span id="text-decoration-skip"></span>
    <span id="text-underline-position"></span>
    <span id="emphasis-marks"></span>
    <span id="text-emphasis-style"></span>
    <span id="text-emphasis-color"></span>
    <span id="text-emphasis"></span>
    <span id="text-emphasis-position"></span>
    <span id="text-shadow"></span>
    Features for decorating text,
    such as <a href="https://www.w3.org/TR/css-text-decor-3/#line-decoration">underlines</a>,
    <a href="https://www.w3.org/TR/css-text-decor-3/#emphasis-marks">emphasis marks</a>,
    and <a href="https://www.w3.org/TR/css-text-decor-3/#text-shadow-property">shadows</a>,
    (previously part of this module)
    are covered in
    <a href="https://www.w3.org/TR/css-text-decor-3/">CSS Text Decoration Level 3</a> [[CSS-TEXT-DECOR-3]].

    <p><a href="https://www.w3.org/TR/css-writing-modes-3/#text-direction">Bidirectional</a> and
    <a href="https://www.w3.org/TR/css-writing-modes-3/#vertical-intro">vertical</a> text
    are addressed in
    <a href="https://www.w3.org/TR/css-writing-modes-3/">CSS Writing Modes Level 3</a> [[CSS-WRITING-MODES-3]].
  </div>

  Further information about the typesetting requirements
  of various languages and writing systems around the world
  can be found in the <a href="https://www.w3.org/International/core/">Internationalization Working Group</a>’s
  <a href="https://www.w3.org/TR/typography/">Typography Index</a>.
  [[TYPOGRAPHY]]

<h3 id="placement">
Module Interactions</h3>

  <p>This module, together with [[CSS-TEXT-DECOR-3]],
  replaces and extends the text-level features defined in [[!CSS2]] chapter 16.

  <p>In addition to the terms defined below,
    other terminology and concepts used in this specification are defined
    in [[!CSS2]] and [[!CSS-WRITING-MODES-3]].

    <!-- Listing level 4 tests as otherwise bikeshed complains -->
    <wpt>
      white-space/text-space-collapse-discard-001.xht
      white-space/text-space-collapse-preserve-breaks-001.xht
      white-space/text-space-trim-trim-inner-001.xht
    </wpt>

<h3 id="values">
Values</h3>

  This specification follows the <a href="https://www.w3.org/TR/CSS2/about.html#property-defs">CSS property definition conventions</a> from [[!CSS2]].
  Value types not defined in this specification are defined in CSS Values & Units [[!CSS-VALUES-3]].
  Other CSS modules may expand the definitions of these value types.

  In addition to the property-specific values listed in their definitions,
  all properties defined in this specification
  also accept the <a>CSS-wide keywords</a> keywords as their property value.
  For readability they have not been repeated explicitly.

<h3 id="languages">
Languages and Typesetting</h3>

  <p><strong class="advisement">
    Authors should language-tag their content accurately for the best typographic behavior.
  </strong>

  <p>The <dfn export>content language</dfn> of an element is the (human) language
    the element is declared to be in, according to the rules of the
    <a href="https://www.w3.org/TR/CSS2/conform.html#doclanguage">document language</a>.
    For example, the rules for determining the <a>content language</a> of an HTML
    are <a href="https://html.spec.whatwg.org/multipage/dom.html#language">defined</a> in [[HTML]],
    and the rules for determining the <a>content language</a> of an XML element use
    are <a href="https://www.w3.org/TR/REC-xml/#sec-lang-tag">defined</a> in [[XML10]].
    Note that it is possible for the <a>content language</a> of an element
    to be unknown--
    e.g. untagged content,
    or content in a <a>document language</a> that does not have a language-tagging facility
    is considered to have an unknown <a>content language</a>.

    Note: Authors can tag content using the global <code>lang</code> attribute in HTML,
    the universal <code>xml:lang</code> attribute in XML,
    and the HTTP <code>Content-Language</code> header for content served over HTTP.

    The [=content language=] an element is declared to be in
    also identifies the specific written form of that language used in that element,
    known as the <dfn export local-lt="writing system">content writing system</dfn>.

    Note: Depending on the [=document language=]'s facilities for identifying the [=content language=],
    information about the [=writing system=] may only be carried implicitly.
    That is typically the case with the [[BCP47]] language tag used in [[HTML]],
    although it can optionally indicate the [=writing system=] explicitly
    using a script subtag.

    Language and writing system conventions can affect
    line breaking, hyphenation, justification, glyph selection,
    and many other typographic effects.
    <strong>In CSS, language-specific typographic tailorings
    are only applied when the <a>content language</a> is known (declared).</strong>
    Therefore,
    higher quality typography requires authors to communicate to the UA
    the correct linguistic context of the text in the document.

    More information about language tags and their interpretation,
    particularly the use of script tags for atypical language + writing-system combinations,
    can be found in [[#script-tagging]].

<h3 id="characters">
Characters and Letters</h3>

  <p>The basic unit of typesetting is the <dfn export>character</dfn>.
  However, because writing systems are not always as simple as the basic English alphabet,
  what a <a>character</a> actually is depends on the context in which the term is used.
  For example, in Hangul (the Korean writing system),
  each square representation of a syllable
  (e.g. <span lang=ko-hang title="Hangul syllable HAN">한</span>=<span lang=ko-Latn>Han</span>)
  can be considered a <a>character</a>.
  However, the square symbol is really composed of multiple letters each representing a phoneme
  (e.g. <span lang=ko-hang title="Hangul letter HIEUH">ㅎ</span>=<span lang=ko-Latn>h</span>,
   <span lang=ko-hang title="Hangul letter HIEUH">ㅏ</span>=<span lang=ko-Latn>a</span>,
   <span lang=ko-hang title="Hangul letter HIEUH">ㄴ</span>=<span lang=ko-Latn>n</span>)
  and these also could each be considered a <a>character</a>.

  <p>A basic unit of computer text encoding, for any given encoding,
  is also called a <a>character</a>,
  and depending on the encoding,
  a single encoding <a>character</a> might correspond
  to the entire pre-composed syllabic <a>character</a> (e.g. <span lang=ko-hang title="Hangul syllable HAN">한</span>),
  to the individual phonemic <a>character</a> (e.g. <span lang=ko-hang title="Hangul letter HIEUH">ㅎ</span>),
  or to smaller units such as
  a base letterform (e.g. <span lang=ko-hang title="Hangul letter IEUNG">ㅇ</span>)
  and any combining marks that vary it (e.g. extra strokes that represent aspiration).

  <p>In turn, a single encoding <a>character</a> can be represented in the data stream as one or more bytes;
  and in programming environments one byte is sometimes also called a <a>character</a>.

  <p>Therefore the term <a>character</a> is fairly ambiguous where technical precision is required.

  <p>For text layout, we will refer to the <dfn export lt="typographic character unit|typographic character">typographic character unit</dfn>
  as the basic unit of text.
  Even within the realm of text layout,
  the relevant <a>character</a> unit depends on the operation.
  For example, line-breaking and letter-spacing will segment
  a sequence of Thai characters that include U+0E33 THAI CHARACTER SARA AM differently;
  or the behaviour of a conjunct consonant in a script such as Devanagari
  may depend on the font in use.
  So the <a>typographic character</a> represents a unit of the writing system&mdash;<!--
  -->such as a Latin alphabetic letter (including its diacritics),
  Hangul syllable,
  Chinese ideographic character,
  Myanmar syllable cluster&mdash;<!--
  -->that is indivisible with respect to a particular typographic operation
  (line-breaking, first-letter effects, tracking, justification, vertical arrangement, etc.).

  <wpt>
    word-break/word-break-break-all-007.html
    word-break/word-break-break-all-008.html
  </wpt>

  <a href="http://www.unicode.org/reports/tr29/">Unicode Standard Annex #29: Text Segmentation</a>
  defines a unit called the <dfn>grapheme cluster</dfn>
  which approximates the <a>typographic character</a>.
  A UA must use the <em>extended grapheme cluster</em>
  (not <em>legacy grapheme cluster</em>), as defined in [[!UAX29]],
  as the basis for its <a>typographic character unit</a>.
  However, the UA should tailor the definitions
  as required by typographic tradition
  since the default rules are not always appropriate or ideal--
  and is expected to tailor them differently
  depending on the operation as needed.

  <wpt>
    line-breaking/line-breaking-013.html
    line-breaking/line-breaking-014.html
  </wpt>

  <p class="note">
  Note: The rules for such tailorings are out of scope for CSS.
<!--
  however W3C currently maintains a wiki page
  where some known tailorings are collected.
-->

  <div class="example">
    The following are some examples of <a>typographic character unit</a> tailorings
    required by standard typesetting practice:

    <ul>
      <li>
        <p>In some scripts such as Myanmar or Devanagari,
        the <a>typographic character unit</a> for both justification and line-breaking
        is an entire syllable,
        which can include more than one [[!UAX29]] <a>grapheme cluster</a>.

      <li>
        <p>In other scripts such as Thai or Lao,
        even though for line-breaking the <a>typographic character</a>
        matches Unicode’s default <a>grapheme clusters</a>,
        for letter-spacing the relevant unit
        is <em>less</em> than a [[!UAX29]] <a>grapheme cluster</a>,
        and may require decomposition or other substitutions
        before spacing can be inserted.

        <p>For instance,
        to properly letter-space the Thai word คำ (U+0E04 + U+0E33),
        the U+0E33 needs to be decomposed into U+0E4D + U+0E32,
        and then the extra letter-space inserted before the U+0E32: คํ า.

        <p>A slightly more complex example is น้ำ (U+0E19 + U+0E49 + U+0E33).
        In this case, normal Thai shaping will first decompose the U+0E33 into U+0E4D + U+0E32
        and then swap the U+0E4D with the U+0E49, giving U+0E19 + U+0E4D + U+0E49 + U+0E32.
        As before the extra letter-space is then inserted before the U+0E32: นํ้ า.

      <li>
        <p>Vertical typesetting [[!CSS-WRITING-MODES-3]] can also require tailoring.
        For example, when typesetting ''text-orientation/upright'' text,
        Tibetan tsek and shad marks are kept with the preceding grapheme cluster,
        rather than treated as an independent <a>typographic character unit</a>.
    </ul>
  </div>

  <p>A <dfn export>typographic letter unit</dfn> or <dfn>letter</dfn> for the purpose of this specification
  is a <a>typographic character unit</a> belonging to one of the Letter or Number general
  categories in Unicode. [[!UAX44]]
  See <a href="#character-properties">Character Properties</a>
  for how to determine the Unicode properties of a <a>typographic character unit</a>.

  <p>The rendering characteristics of a <a>typographic character unit</a> divided
  by an element boundary is undefined.
  Ideally each component should be rendered
  according to the formatting requirements of its respective element’s properties
  while maintaining correct shaping and positioning
  of the <a>typographic character unit</a> as a whole.
  However, depending on the nature of the formatting differences between its parts
  and the capabilities of the font technology in use,
  this is not always possible.
  Therefore such a <a>typographic character unit</a>
  may be rendered as belonging to either side of the boundary,
  or as some approximation of belonging to both.
  Authors are forewarned that dividing <a>grapheme clusters</a>
  by element boundaries may give inconsistent or undesired results.

<h3 id="text-encoding">
Text Processing</h3>

  CSS is built on [[UNICODE]].
  UAs that support Unicode must adhere to all normative requirements
  of the Unicode Core Standard,
  except where explicitly overridden by CSS.
  UAs that use a different encoding are not explicitly supported by the CSS specifications;
  they are, however, expected to fulfill the same text handling requirements
  by assuming an appropriate mapping between that encoding and Unicode.

  <wpt>
    text-encoding/shaping-join-001.html
    text-encoding/shaping-join-002.html
    text-encoding/shaping-join-003.html
    text-encoding/shaping-no-join-001.html
    text-encoding/shaping-no-join-002.html
    text-encoding/shaping-no-join-003.html
    text-encoding/shaping-tatweel-001.html
    text-encoding/shaping-tatweel-002.html
    text-encoding/shaping-tatweel-003.html
  </wpt>

<h2 id="transforming">
  Transforming Text</h2>

  <h3 id="text-transform-property" oldids="text-transform caps-prop">
    Case Transforms: the 'text-transform' property</h3>

    <pre class="propdef">
    Name: text-transform
    Value: none | [capitalize | uppercase | lowercase ] || full-width || full-size-kana
    Initial: none
    Applies to: <a>inline boxes</a>
    Inherited: yes
    Canonical order: n/a
    Computed value: specified keyword
    Animation type: discrete
    </pre>

    <wpt>
      inheritance.html
      parsing/text-transform-valid.html
      parsing/text-transform-invalid.html
      text-transform/text-transform-multiple-001.html
    </wpt>

    <p>This property transforms text for styling purposes.
    It has no effect on the underlying content,
    and must not affect the content of a plain text copy &amp; paste operation.

    <wpt>
      text-transform/text-transform-copy-paste-001-manual.html
    </wpt>

    <p>Values have the following meanings:

    <dl dfn-for=text-transform dfn-type=value>
      <dt><dfn>none</dfn></dt>
        <dd>No effects.
          <wpt>
            text-transform/text-transform-none-001.xht
          </wpt>
        </dd>
      <dt><dfn>capitalize</dfn></dt>
        <dd>Puts the first <a>typographic letter unit</a> of each word, if lowercase, in titlecase;
          other characters are unaffected.

          <wpt>
            text-transform/text-transform-capitalize-001.html
            text-transform/text-transform-capitalize-003.html
            text-transform/text-transform-capitalize-005.html
            text-transform/text-transform-capitalize-007.html
            text-transform/text-transform-capitalize-009.html
            text-transform/text-transform-capitalize-010.html
            text-transform/text-transform-capitalize-011.html
            text-transform/text-transform-capitalize-014.html
            text-transform/text-transform-capitalize-016.html
            text-transform/text-transform-capitalize-018.html
            text-transform/text-transform-capitalize-020.html
            text-transform/text-transform-capitalize-022.html
            text-transform/text-transform-capitalize-024.html
            text-transform/text-transform-capitalize-026.html
            text-transform/text-transform-capitalize-028.html
            text-transform/text-transform-capitalize-030.html
            text-transform/text-transform-capitalize-031.html
            text-transform/text-transform-capitalize-032.xht
          </wpt>
        </dd>
      <dt><dfn>uppercase</dfn></dt>
        <dd>Puts all <a>letters</a> in uppercase.
          <wpt>
            text-transform/text-transform-uppercase-001.xht
            text-transform/text-transform-upperlower-001.html
            text-transform/text-transform-upperlower-003.html
            text-transform/text-transform-upperlower-005.html
            text-transform/text-transform-upperlower-007.html
            text-transform/text-transform-upperlower-009.html
            text-transform/text-transform-upperlower-011.html
            text-transform/text-transform-upperlower-015.html
            text-transform/text-transform-upperlower-017.html
            text-transform/text-transform-upperlower-019.html
            text-transform/text-transform-upperlower-021.html
            text-transform/text-transform-upperlower-023.html
            text-transform/text-transform-upperlower-025.html
            text-transform/text-transform-upperlower-027.html
            text-transform/text-transform-upperlower-029.html
            text-transform/text-transform-upperlower-031.html
            text-transform/text-transform-upperlower-101.html
            text-transform/text-transform-upperlower-103.html
          </wpt>
      <dt><dfn>lowercase</dfn></dt>
        <dd>Puts all <a>letters</a> in lowercase.
          <wpt>
            text-transform/text-transform-lowercase-001.xht
            text-transform/text-transform-lowercase-002.xht
            text-transform/text-transform-upperlower-002.html
            text-transform/text-transform-upperlower-004.html
            text-transform/text-transform-upperlower-006.html
            text-transform/text-transform-upperlower-008.html
            text-transform/text-transform-upperlower-010.html
            text-transform/text-transform-upperlower-012.html
            text-transform/text-transform-upperlower-014.html
            text-transform/text-transform-upperlower-016.html
            text-transform/text-transform-upperlower-018.html
            text-transform/text-transform-upperlower-020.html
            text-transform/text-transform-upperlower-022.html
            text-transform/text-transform-upperlower-024.html
            text-transform/text-transform-upperlower-026.html
            text-transform/text-transform-upperlower-028.html
            text-transform/text-transform-upperlower-030.html
            text-transform/text-transform-upperlower-102.html
            text-transform/text-transform-upperlower-104.html
          </wpt>
        </dd>
      <dt><dfn>full-width</dfn></dt>
        <dd>Puts all <a>typographic character units</a> in fullwidth form.
          If a character does not have a corresponding fullwidth form,
          it is left as is.
          This value is typically used to typeset Latin letters and digits
          as if they were ideographic characters.

          <wpt>
            text-transform/text-transform-fullwidth-001.xht
            text-transform/text-transform-fullwidth-002.xht
            text-transform/text-transform-fullwidth-004.xht
            text-transform/text-transform-fullwidth-005.xht
          </wpt>
      <dt><dfn>full-size-kana</dfn></dt>
        <dd>Converts all [=small Kana=] characters to the equivalent [=full-size Kana=].
          This value is typically used for ruby annotation text,
          where authors may want all small Kana to be drawn as large Kana
          to compensate for legibility issues at the small font sizes typically used in ruby.
          <wpt>
            text-transform/text-transform-full-size-kana-001.html
            text-transform/text-transform-full-size-kana-002.html
            text-transform/text-transform-full-size-kana-003.html
            text-transform/text-transform-full-size-kana-004.html
            text-transform/text-transform-full-size-kana-005.html
            text-transform/text-transform-full-size-kana-006.html
            text-transform/text-transform-full-size-kana-007.html
          </wpt>
    </dl>

    <p>For ''capitalize'', what constitutes a “word“ is UA-dependent;
      [[!UAX29]] is suggested (but not required)
      for determining such word boundaries.
      Authors should not expect ''capitalize'' to follow
      language-specific titlecasing conventions
      (such as skipping articles in English).
      Out-of-flow elements and inline element boundaries
      must not introduce a 'text-transform' word boundary
      and must be ignored when determining such word boundaries.

      <wpt>
        text-transform/text-transform-capitalize-033.html
      </wpt>

    <div class="example">
      <p>The following example converts the ASCII characters
        used in abbreviations in Japanese text to their fullwidth variants
        so that they lay out and line break like ideographs:
      <pre>abbr:lang(ja) { text-transform: full-width; }</pre>
    </div>

    <p class="note">
      Note: As defined in <a href="#order">Text Processing Order of Operations</a>,
      transforming text affects line-breaking and other formatting operations.

    <p>
      The UA must use the full case mappings for Unicode
      characters, including any conditional casing rules, as defined in
      Default Case Algorithm section of The Unicode Standard [[!UNICODE]].
      If (and only if) the <a>content language</a>
      of the element is, according to the rules of the
      <a href="https://www.w3.org/TR/CSS2/conform.html#doclanguage">document language</a>,
      known,
      then any appropriate language-specific rules must be applied as well.
      These minimally include, but are not limited to, the language-specific
      rules in Unicode's
      <a href="http://www.unicode.org/Public/UNIDATA/SpecialCasing.txt">SpecialCasing.txt</a>.

      <wpt>
        writing-system/writing-system-text-transform-001.html
        text-transform/text-transform-tailoring-001.html
        text-transform/text-transform-tailoring-002.html
        text-transform/text-transform-tailoring-002a.html
        text-transform/text-transform-tailoring-003.html
        text-transform/text-transform-tailoring-004.html
        text-transform/text-transform-tailoring-005.html
        text-transform/text-transform-upperlower-032.html
        text-transform/text-transform-upperlower-033.html
        text-transform/text-transform-upperlower-034.html
        text-transform/text-transform-upperlower-035.html
        text-transform/text-transform-upperlower-038.html
        text-transform/text-transform-upperlower-039.html
        text-transform/text-transform-upperlower-040.html
        text-transform/text-transform-upperlower-041.html
        text-transform/text-transform-upperlower-042.html
        text-transform/text-transform-upperlower-043.html
      </wpt>

    <div class="example">
      <p>For example, in Turkish there are two &ldquo;i&rdquo;s, one with
        a dot&mdash;&ldquo;İ&rdquo; and &ldquo;i&rdquo;&mdash; and one
        without&mdash;&ldquo;I&rdquo; and &ldquo;ı&rdquo;. Thus the usual
        case mappings between &ldquo;I&rdquo; and &ldquo;i&rdquo; are
        replaced with a different set of mappings to their respective
        undotted/dotted counterparts, which do not exist in English. This
        mapping must only take effect if the <a>content language</a> is Turkish
        written in its modern Latin-based <a>writing system</a>
        (or another Turkic language that uses Turkish casing rules);
        in other languages, the usual mapping of &ldquo;I&rdquo;
        and &ldquo;i&rdquo; is required. This rule is thus conditionally
        defined in Unicode's SpecialCasing.txt file.
    </div>

    <p>The definition of fullwidth and halfwidth forms can be found on the
      Unicode consortium web site at [[!UAX11]].
      The mapping to fullwidth form is defined by taking code points with
      the <code>&lt;wide&gt;</code> or the <code>&lt;narrow&gt;</code> tag
      in their <code>Decomposition_Mapping</code> in [[!UAX44]].
      For the <code>&lt;narrow&gt;</code> tag,
      the mapping is from the code point to the decomposition (minus <code>&lt;narrow&gt;</code> tag),
      and for the <code>&lt;wide&gt;</code> tag,
      the mapping is from the decomposition (minus the <code>&lt;wide&gt;</code> tag)
      back to the original code point.

      <wpt>
        text-transform/text-transform-fullwidth-001.xht
        text-transform/text-transform-fullwidth-002.xht
        text-transform/text-transform-fullwidth-004.xht
        text-transform/text-transform-fullwidth-005.xht
      </wpt>

    <p>The mappings for small Kana to full-size Kana are defined in [[#small-kana]].

    <p>When multiple values are specified and therefore multiple transformations need to be applied,
      they are applied in the following order:
    <ol>
      <li>''capitalize'', ''upercase'', and ''lowercase''
      <li>''full-width''
      <li>''full-size-kana''
    </ol>

    <wpt>
      text-transform/text-transform-multiple-001.html
    </wpt>

    <p>Text transformation happens after <a href="#white-space-rules">white
      space processing</a>, which means that ''full-width'' only transforms
      U+0020 spaces to U+3000 within <a>preserved</a> white space.

    <p class="note">
      Note: A future level of CSS may introduce the ability to create custom mapping
      tables for less common text transforms, such as by an ''@text-transform''
      rule similar to ''@counter-style'' from [[CSS-COUNTER-STYLES-3]].


<h2 id="white-space-property" oldids="white-space-collapsing text-wrap">
  White Space and Wrapping: the 'white-space' property</h2>

  <pre class="propdef">
  Name: white-space
  Value: normal | pre | nowrap | pre-wrap | break-spaces | pre-line
  Initial: normal
  Applies to: <a>inline boxes</a>
  Inherited: yes
  Canonical order: n/a
  Computed value: specified keyword
  Animation type: discrete
  </pre>

  <wpt>
    inheritance.html
    parsing/white-space-valid.html
    parsing/white-space-invalid.html
  </wpt>
  <wpt pathprefix="/css/CSS2/css1/">
    c562-white-sp-000.xht
  </wpt>
  <wpt pathprefix="/css/CSS2/text/">
    white-space-006.xht
    white-space-007.xht
    white-space-applies-to-001.xht
    white-space-mixed-001.xht
    white-space-mixed-002.xht
    white-space-mixed-003.xht
    <!-- manual test
    white-space-mixed-004.xht
    -->
  </wpt>

  <p>This property specifies two things:
  <ul>
    <li>whether and how <a>white space</a> inside the element is collapsed
    <li>whether lines may <a>wrap</a> at unforced <a>soft wrap opportunities</a>
  </ul>

  <p>Values have the following meanings, which must be interpreted
    according to
    the <a href="#white-space-rules">White Space Processing</a> and
    <a href="#line-breaking">Line Breaking</a> rules:</p>

  <dl dfn-for=white-space dfn-type=value>
    <dt><dfn>normal</dfn></dt>
    <dd>This value directs user agents to collapse sequences of <a>white space</a>
      into a single character (or <a href="#line-break-transform">in some
      cases</a>, no character).
      Lines may wrap at allowed <a>soft wrap opportunities</a>,
      as determined by the line-breaking rules in effect,
      in order to minimize inline-axis overflow.

      <wpt>
        white-space/white-space-wrap-after-nowrap-001.html
      </wpt>
      <wpt pathprefix="/css/CSS2/text/">
        white-space-normal-001.xht
        white-space-normal-002.xht
        white-space-normal-003.xht
        white-space-normal-004.xht
        white-space-normal-005.xht
        white-space-normal-006.xht
        white-space-normal-007.xht
        white-space-normal-008.xht
        white-space-normal-009.xht
      </wpt>
    <dt><dfn>pre</dfn></dt>
    <dd>This value prevents user agents from collapsing sequences of <a>white space</a>.
      <a>Segment breaks</a> such as line feeds
      are preserved as <a>forced line breaks</a>.
      Lines only break at <a>forced line breaks</a>;
      content that does not fit within the block container overflows it.

      <wpt pathprefix="/css/CSS2/text/">
        white-space-pre-001.xht
        white-space-pre-002.xht
        white-space-pre-005.xht
        white-space-pre-006.xht
        <!--manual test
        white-space-pre-007.xht
        -->
      </wpt>
    <dt><dfn>nowrap</dfn>
    <dd>Like ''white-space/normal'', this value collapses <a>white space</a>;
      but like ''pre'', it does not allow wrapping.

      <wpt>
        white-space/white-space-wrap-after-nowrap-001.html
        white-space/nowrap-wbr-and-space-crash.html
      </wpt>
      <wpt pathprefix="/css/CSS2/text/">
        white-space-nowrap-001.xht
        white-space-nowrap-005.xht
        white-space-nowrap-006.xht
      </wpt>
    <dt><dfn>pre-wrap</dfn></dt>
    <dd>Like ''pre'', this value preserves <a>white space</a>;
      but like ''white-space/normal'', it allows wrapping.

      <wpt>
        white-space/pre-wrap-001.html
        white-space/pre-wrap-002.html
        white-space/pre-wrap-003.html
        white-space/pre-wrap-004.html
        white-space/pre-wrap-005.html
        white-space/pre-wrap-006.html
        white-space/pre-wrap-007.html
        white-space/pre-wrap-011.html
        white-space/pre-wrap-012.html
        white-space/pre-wrap-013.html
        white-space/pre-wrap-014.html
        white-space/textarea-pre-wrap-001.html
        white-space/textarea-pre-wrap-002.html
        white-space/textarea-pre-wrap-003.html
        white-space/textarea-pre-wrap-004.html
        white-space/textarea-pre-wrap-005.html
        white-space/textarea-pre-wrap-006.html
        white-space/textarea-pre-wrap-007.html
        white-space/textarea-pre-wrap-011.html
        white-space/textarea-pre-wrap-012.html
        white-space/textarea-pre-wrap-013.html
        white-space/textarea-pre-wrap-014.html
        white-space/white-space-pre-wrap-trailing-spaces-001.html
        white-space/white-space-pre-wrap-trailing-spaces-002.html
        white-space/white-space-pre-wrap-trailing-spaces-003.html
      </wpt>
    <dt><dfn>break-spaces</dfn></dt>
    <dd>The behavior is identical to that of ''white-space/pre-wrap'',
      except that:
      * Any sequence of <a>preserved</a> white space always takes up space,
        including at the end of the line.
      * A line breaking opportunity exists after every <a>preserved</a> <a>white space</a> character,
        including between white space characters.

        <wpt>
          overflow-wrap/overflow-wrap-break-word-002.html
          overflow-wrap/overflow-wrap-anywhere-002.html
          white-space/break-spaces-001.html
          white-space/break-spaces-002.html
          white-space/break-spaces-003.html
          white-space/break-spaces-004.html
          white-space/break-spaces-005.html
          white-space/break-spaces-006.html
          white-space/break-spaces-007.html
          white-space/break-spaces-008.html
          white-space/break-spaces-009.html
          white-space/textarea-break-spaces-001.html
          white-space/textarea-break-spaces-002.html
          white-space/tab-stop-threshold-005.html
          white-space/tab-stop-threshold-006.html
        </wpt>

      Such preserved spaces take up space and do not hang,
      and thus affect the box's intrinsic sizes
      ([=min-content size=] and [=max-content size=]).

      <wpt>
        white-space/white-space-intrinsic-size-001.html
        white-space/white-space-intrinsic-size-002.html
      </wpt>

      <p class="note">Note: This value does not guarantee that there will never be any overflow due to spaces:
      for example, if the line length is so short that even a single space does not fit,
      overflow is unavoidable.</p>

    <dt><dfn>pre-line</dfn></dt>
    <dd>Like ''white-space/normal'', this value collapses consecutive spaces and allows wrapping,
      but preserves <a>segment breaks</a> in the source as <a>forced line breaks</a>.

      <wpt pathprefix="/css/CSS2/text/">
        white-space-005.xht
        white-space-generated-content-before-001.xht
        white-space-processing-004.xht
        white-space-processing-010.xht
        white-space-processing-017.xht
        white-space-processing-021.xht
        white-space-processing-024.xht
        white-space-processing-027.xht
        white-space-processing-028.xht
        white-space-processing-029.xht
        white-space-processing-030.xht
        white-space-processing-035.xht
        white-space-processing-036.xht
        white-space-processing-045.xht
        white-space-processing-053.xht
      </wpt>
  </dl>

  <p>[=White space=] that was not removed or collapsed due to white space processing
    is called <dfn local-lt="preserved">preserved white space</dfn>.
    In general, <a>preserved white space</a> is measured when calculating
    the intrinsic sizes ([=min-content size=] and [=max-content size=]) of text;
    however <a>preserved white space</a>
    that would be allowed to <a>hang</a> at the end of the line
    (i.e. that preserved by ''pre-wrap'')
    is excluded--
    that is, considered to <a>hang</a>--
    when calculating <a>min-content sizes</a> and any sizes derived thereof.

  <p>The following informative table summarizes the behavior of various
    'white-space' values:</p>

  <table class="data">
    <colgroup class="header"></colgroup>
    <colgroup span=4></colgroup>
    <thead>
      <tr>
        <th></th>
        <th>New Lines</th>
        <th>Spaces and Tabs</th>
        <th>Text Wrapping</th>
        <th>End-of-line spaces</th>
      </tr>
    </thead>
    <tbody>
      <tr>
        <th>''white-space/normal''</th>
        <td>Collapse</td>
        <td>Collapse</td>
        <td>Wrap</td>
	<td>Remove</td>
      </tr>
      <tr>
        <th>''pre''</th>
        <td>Preserve</td>
        <td>Preserve</td>
        <td>No wrap</td>
	<td>Preserve</td>
      </tr>
      <tr>
        <th>''nowrap''</th>
        <td>Collapse</td>
        <td>Collapse</td>
        <td>No wrap</td>
	<td>Remove</td>
      </tr>
      <tr>
        <th>''pre-wrap''</th>
        <td>Preserve</td>
        <td>Preserve</td>
        <td>Wrap</td>
	<td>Hang</td>
      </tr>
      <tr>
        <th>''break-spaces''</th>
        <td>Preserve</td>
        <td>Preserve</td>
        <td>Wrap</td>
        <td>Wrap</td>
      </tr>
      <tr>
        <th>''pre-line''</th>
        <td>Preserve</td>
        <td>Collapse</td>
        <td>Wrap</td>
        <td>Remove</td>
    </tbody>
  </table>

  <p>See <a href="#white-space-processing">White Space Processing Rules</a>
    for details on how white space collapses. An informative summary of
    collapsing (''white-space/normal'' and ''nowrap'') is presented below:
    <ul>
      <li>A sequence of segment breaks and other <a>white space</a> between two
        Chinese, Japanese, or Yi characters collapses into nothing.
      <li>A zero width space before or after a white space sequence
        containing a segment break causes the entire sequence of <a>white space</a>
        to collapse into a zero width space.
      <li>Otherwise, consecutive <a>white space</a> collapses into a single space.
    </ul>

  <p>See <a href="#line-breaking">Line Breaking</a>
    for details on wrapping behavior.

<h2 id="white-space-processing">
  White Space Processing Details</h2>

  <p>The source text of a document often contains formatting
    that is not relevant to the final rendering: for example,
    <a href="http://rhodesmill.org/brandon/2012/one-sentence-per-line/">breaking the source into segments</a>
    (lines) for ease of editing
    or adding white space characters such as tabs and spaces to indent the source code.
    CSS white space processing allows the author to control interpretation of such formatting:
    to preserve or collapse it away when rendering the document.
    White space processing in CSS interprets white space characters only for rendering:
    it has no effect on the underlying document data.

  <p>White space processing in CSS is controlled with the 'white-space' property.

  <p id="segment-normalization">
    CSS does not define document segmentation rules. Segments can be
    separated by a particular newline sequence (such as a line feed or
    CRLF pair), or delimited by some other mechanism, such as the SGML
    <code>RECORD-START</code> and <code>RECORD-END</code> tokens.
    For CSS processing, each document language&ndash;defined segment break
    and each line feed (U+000A)
    in the text is treated as a <dfn export>segment break</dfn>,
    which is then interpreted for rendering as specified by the 'white-space' property.

  <p class="note">Note: A document parser might
    not only normalize any <a>segment breaks</a>,
    but also collapse other space characters or
    otherwise process white space according to markup rules.
    Because CSS processing occurs <em>after</em> the parsing stage,
    it is not possible to restore these characters for styling.
    Therefore, some of the behavior specified below
    can be affected by these limitations and
    may be user agent dependent.</p>

  <p class="note">Note: Anonymous blocks consisting entirely of
    <a>collapsible</a> <a>white space</a> are removed from the rendering tree.
    Thus any such <a>white space</a> surrounding a block-level element is collapsed away.
    See [[CSS2]] section
    <a href="https://www.w3.org/TR/CSS2/visuren.html#anonymous">9.2.2.1</a></p>

  <p>
    Control characters (<a>Unicode category</a> <code>Cc</code>)--
    other than tabs (U+0009), line feeds (U+000A),
    and sequences that form a <a>segment break</a>--
    must be rendered as a visible glyph
    which the UA must synthethize if the glyphs found in the font are not visible,
    and must be otherwise treated as any other character
    of the Other Symbols (<code>So</code>) <a>general category</a> and Common <a lt="Unicode script">script</a>.
    The UA may use a glyph provided by a font specifically for the control character,
    substitute the glyphs provided for the corresponding symbol in the Control Pictures block,
    generate a visual representation of its code point value,
    or use some other method to provide an appropriate visible glyph.
    As required by [[!UNICODE]],
    unsupported <code>Default_ignorable</code> characters must be ignored for rendering.

    <wpt>
      white-space/control-chars-000.html
      white-space/control-chars-001.html
      white-space/control-chars-002.html
      white-space/control-chars-003.html
      white-space/control-chars-004.html
      white-space/control-chars-005.html
      white-space/control-chars-006.html
      white-space/control-chars-007.html
      white-space/control-chars-008.html
      white-space/control-chars-00B.html
      white-space/control-chars-00C.html
      white-space/control-chars-00D.html
      white-space/control-chars-00E.html
      white-space/control-chars-00F.html
      white-space/control-chars-010.html
      white-space/control-chars-011.html
      white-space/control-chars-012.html
      white-space/control-chars-013.html
      white-space/control-chars-014.html
      white-space/control-chars-015.html
      white-space/control-chars-016.html
      white-space/control-chars-017.html
      white-space/control-chars-018.html
      white-space/control-chars-019.html
      white-space/control-chars-01A.html
      white-space/control-chars-01B.html
      white-space/control-chars-01C.html
      white-space/control-chars-01D.html
      white-space/control-chars-01E.html
      white-space/control-chars-01F.html
      white-space/control-chars-07F.html
      white-space/control-chars-080.html
      white-space/control-chars-081.html
      white-space/control-chars-082.html
      white-space/control-chars-083.html
      white-space/control-chars-084.html
      white-space/control-chars-085.html
      white-space/control-chars-086.html
      white-space/control-chars-087.html
      white-space/control-chars-088.html
      white-space/control-chars-089.html
      white-space/control-chars-08A.html
      white-space/control-chars-08B.html
      white-space/control-chars-08C.html
      white-space/control-chars-08D.html
      white-space/control-chars-08E.html
      white-space/control-chars-08F.html
      white-space/control-chars-090.html
      white-space/control-chars-091.html
      white-space/control-chars-092.html
      white-space/control-chars-093.html
      white-space/control-chars-094.html
      white-space/control-chars-095.html
      white-space/control-chars-096.html
      white-space/control-chars-097.html
      white-space/control-chars-098.html
      white-space/control-chars-099.html
      white-space/control-chars-09A.html
      white-space/control-chars-09B.html
      white-space/control-chars-09C.html
      white-space/control-chars-09D.html
      white-space/control-chars-09E.html
      white-space/control-chars-09F.html
    </wpt>

  <h3 id="white-space-rules">
    The White Space Processing Rules</h3>

    <p>White space processing in CSS affects only
      the <dfn export lt="white space|white space characters| document white space|document white space characters">document white space characters</dfn>:
      spaces (U+0020), tabs (U+0009), and <a href="#white-space-processing">segment breaks</a>.

      <wpt pathprefix="/css/CSS2/text/">
        white-space-normal-003.xht
        white-space-normal-004.xht
        white-space-normal-005.xht
        white-space-normal-006.xht
        white-space-normal-007.xht
        white-space-normal-008.xht
        white-space-nowrap-005.xht
        white-space-nowrap-006.xht
        white-space-pre-005.xht
        white-space-pre-006.xht
        white-space-processing-054.xht
        white-space-processing-055.xht
        white-space-processing-056.xht
      </wpt>

    <p class="note">
      Note: The set of characters considered <a>document white space</a> (part of the document content)
      and that considered syntactic white space (part of the CSS syntax)
      are not necessarily identical.
      However, since both include spaces (U+0020), tabs (U+0009), and line feeds (U+000A)
      most authors won't notice any differences.

    <h4 id="white-space-phase-1">Phase I: Collapsing and Transformation</h4>

    <p>For each inline (including anonymous inlines;
      see [[CSS2]] section <a href="https://www.w3.org/TR/CSS2/visuren.html#anonymous">9.2.2.1</a>)
      within an inline
      formatting context, white space characters are handled as follows,
      ignoring <dfn noexport>bidi formatting characters</dfn>
      (characters with the <code>Bidi_Control</code> property [[!UAX9]])
      as if they were not there:

      <wpt>
        white-space/white-space-collapse-002.html
      </wpt>

    <ul>
    <li id="collapse"><p>If 'white-space' is set to
      ''white-space/normal'', ''nowrap'', or ''pre-line'',
      white space characters are considered <dfn export lt="collapsible white space|collapsible">collapsible</dfn>
      and are processed by performing the following steps:</p>
      <ol>
        <li>Any sequence of collapsible spaces and tabs
          immediately preceding or following a <a>segment break</a>
          is removed.

          <wpt>
            white-space/seg-break-transformation-000.html
          </wpt>
          <wpt pathprefix="/css/CSS2/text/">
            white-space-processing-002.xht
            white-space-processing-003.xht
            white-space-processing-004.xht
            white-space-processing-008.xht
            white-space-processing-009.xht
            white-space-processing-010.xht
          </wpt>
        </li>
        <li>Collapsible <a>segment breaks</a> are transformed for
          rendering according to the <a href="#line-break-transform">segment break transformation rules</a>.
        </li>
        <li>Every collapsible tab is converted to a collapsible space (U+0020).

          <wpt>
            white-space/white-space-collapse-000.html
          </wpt>
          <wpt pathprefix="/css/CSS2/text/">
            white-space-processing-019.xht
            white-space-processing-020.xht
            white-space-processing-021.xht
          </wpt>
        </li>
        <li>Any collapsible space immediately following another collapsible space&mdash;even
          one outside the boundary of the inline containing that space,
          provided both spaces are within the same inline formatting
          context&mdash;is collapsed to have zero advance width. (It is
          invisible, but retains its <a>soft wrap opportunity</a>, if any.)

          <wpt>
            white-space/white-space-collapse-001.html
            white-space/white-space-empty-text-sibling.html
          </wpt>
          <wpt pathprefix="/css/CSS2/text/">
	    white-space-001.xht
	    white-space-003.xht
	    white-space-005.xht
            white-space-collapsing-001.xht
            white-space-collapsing-002.xht
            white-space-collapsing-004.xht
            white-space-collapsing-005.xht
            white-space-collapsing-breaks-001.xht
            white-space-mixed-001.xht
            white-space-mixed-002.xht
            white-space-normal-001.xht
            white-space-processing-001.xht
            white-space-processing-022.xht
            white-space-processing-023.xht
            white-space-processing-024.xht
            white-space-processing-025.xht
            white-space-processing-026.xht
            white-space-processing-027.xht
            white-space-processing-028.xht
            white-space-processing-029.xht
            white-space-processing-030.xht
            white-space-processing-031.xht
            white-space-processing-032.xht
            white-space-processing-033.xht
            white-space-processing-034.xht
            white-space-processing-035.xht
            white-space-processing-036.xht
            white-space-processing-050.xht
            white-space-processing-051.xht
            white-space-processing-053.xht
          </wpt>
        </li>
      </ol>
    </li>
    <li><p>If 'white-space' is set to ''pre'', ''pre-wrap'', or ''break-spaces'',
      any sequence of spaces is treated as a sequence of non-breaking spaces.
      However, for ''pre-wrap'',
      a <a>soft wrap opportunity</a> exists at the end of the sequence,
      while for ''break-spaces'',
      a <a>soft wrap opportunity</a> exists after every space.
      <wpt>
        overflow-wrap/overflow-wrap-break-word-004.html
        overflow-wrap/overflow-wrap-break-word-005.html
        overflow-wrap/overflow-wrap-break-word-006.html
        overflow-wrap/overflow-wrap-break-word-007.html
        overflow-wrap/overflow-wrap-anywhere-004.html
        overflow-wrap/overflow-wrap-anywhere-005.html
        word-break/word-break-break-all-011.html
        word-break/word-break-break-all-012.html
        word-break/word-break-break-all-013.html
        word-break/word-break-break-all-015.html
        white-space/break-spaces-006.html
        white-space/break-spaces-007.html
        white-space/break-spaces-008.html
        white-space/break-spaces-009.html
        white-space/pre-wrap-008.html
        white-space/pre-wrap-015.html
        white-space/pre-wrap-016.html
      </wpt>
      <wpt pathprefix="/css/CSS2/text/">
        white-space-002.xht
        white-space-004.xht
        white-space-processing-011.xht
        white-space-processing-012.xht
        white-space-processing-013.xht
        white-space-processing-052.xht
      </wpt>

    <p>Then, the entire block is rendered. Inlines are laid out, taking bidi
      reordering into account, and <a>wrapping</a> as specified by the
      'white-space' property.</p>

      <wpt pathprefix="/css/CSS2/">
        bidi-text/bidi-002.xht
        bidi-text/bidi-004.xht
        bidi-text/line-breaking-bidi-001.xht
        bidi-text/line-breaking-bidi-002.xht
        bidi-text/line-breaking-bidi-003.xht
      </wpt>
      <wpt pathprefix="/css/CSS2/text/">
        white-space-collapsing-bidi-001.xht
        white-space-collapsing-bidi-002.xht
      </wpt>

    <div class="example" id="egbidiwscollapse">
      <p>The following example illustrates
        the interaction of white-space collapsing and bidirectionality.
        Consider the following markup fragment, taking special note of spaces
        (with varied backgrounds and borders for emphasis and identification):

      <pre><code>&lt;ltr&gt;A<span class="egbidiwsaA">&#160;</span>&lt;rtl&gt;<span class="egbidiwsbB">&#160;</span>B<span class="egbidiwsaB">&#160;</span>&lt;/rtl&gt;<span class="egbidiwsbC">&#160;</span>C&lt;/ltr&gt;</code></pre>

      <p>where the <code>&lt;ltr&gt;</code> element represents a left-to-right embedding
        and the <code>&lt;rtl&gt;</code> element represents a right-to-left embedding.
        If the 'white-space' property is set to ''white-space/normal'',
        the white-space processing model will result in the following:

      <ul style="line-height:1.3">
        <li>The space before the B (<span class="egbidiwsbB">&#160;</span>)
          will collapse with the space after the A (<span class="egbidiwsaA">&#160;</span>).
        <li>The space before the C (<span class="egbidiwsbC">&#160;</span>)
          will collapse with the space after the B (<span class="egbidiwsaB">&#160;</span>).
      </ul>

      <p>This will leave two spaces,
        one after the A in the left-to-right embedding level,
        and one after the B in the right-to-left embedding level.
        The text will then be ordered according to the Unicode bidirectional algorithm,
        with the end result being:

      <pre>A<span class="egbidiwsaA">&#160;</span><span class="egbidiwsaB">&#160;</span>BC</pre>

      <p>Note that there will be two spaces between A and B,
        and none between B and C.
        This is best avoided by putting spaces outside the element
        instead of just inside the opening and closing tags and, where practical,
        by relying on implicit bidirectionality instead of explicit embedding levels.
    </div>

    <wpt pathprefix="/css/CSS2/text/">
      white-space-bidirectionality-001.xht
    </wpt>

    <h4 id="line-break-transform">
      Segment Break Transformation Rules</h4>

      <p>When 'white-space' is ''pre'', ''pre-wrap'', ''break-spaces'', or ''pre-line'',
      <a>segment breaks</a> are not <a>collapsible</a>
      and are instead transformed into a preserved line feed (U+000A).

      <wpt pathprefix="/css/CSS2/text/">
        white-space-008.xht
        white-space-processing-016.xht
        white-space-processing-017.xht
        white-space-processing-018.xht
      </wpt>

      <p>For other values of 'white-space', <a>segment breaks</a> are <a>collapsible</a>.
        Any collapsible <a>segment break</a> immediately following another collapsible <a>segment break</a>
        is removed.
        Then any remaining <a>segment break</a> is
        either transformed into a space (U+0020) or removed
        depending on the context before and after the break:

        <wpt pathprefix="/css/vendor-imports/mozilla/mozilla-central-reftests/text3/">
          segment-break-transformation-removable-2.html
          segment-break-transformation-removable-4.html
        </wpt>

      <ul>
        <li>If the character immediately before or immediately after the segment
          break is the zero-width space character (U+200B), then the break
          is removed, leaving behind the zero-width space.

          <wpt>
            white-space/seg-break-transformation-016.html
            white-space/seg-break-transformation-017.html
          </wpt>
          <wpt pathprefix="/css/vendor-imports/mozilla/mozilla-central-reftests/text3/">
            segment-break-transformation-removable-1.html
            segment-break-transformation-removable-3.html
          </wpt>
        <li>Otherwise, if the <a>East Asian Width property</a> [[!UAX11]] of both
          the character before and after the segment break is
          <code>Fullwidth</code>, <code>Wide</code>, or <code>Halfwidth</code>
          (not <code>Ambiguous</code>),
          and neither side is Hangul,
          then the segment break is removed.

          <wpt>
            white-space/seg-break-transformation-001.html
            white-space/seg-break-transformation-002.html
            white-space/seg-break-transformation-003.html
            white-space/seg-break-transformation-004.html
            white-space/seg-break-transformation-005.html
            white-space/seg-break-transformation-006.html
            white-space/seg-break-transformation-007.html
            white-space/seg-break-transformation-008.html
            white-space/seg-break-transformation-009.html
            white-space/seg-break-transformation-010.html
            white-space/seg-break-transformation-011.html
            white-space/seg-break-transformation-012.html
            white-space/seg-break-transformation-014.html
            white-space/seg-break-transformation-015.html
          </wpt>
          <wpt pathprefix="/css/vendor-imports/mozilla/mozilla-central-reftests/text3/">
            segment-break-transformation-rules-001.html
            segment-break-transformation-rules-002.html
            segment-break-transformation-rules-003.html
            segment-break-transformation-rules-004.html
            segment-break-transformation-rules-005.html
            segment-break-transformation-rules-006.html
            segment-break-transformation-rules-007.html
            segment-break-transformation-rules-008.html
            segment-break-transformation-rules-009.html
            segment-break-transformation-rules-010.html
            segment-break-transformation-rules-011.html
            segment-break-transformation-rules-012.html
            segment-break-transformation-rules-013.html
            segment-break-transformation-rules-014.html
            segment-break-transformation-rules-015.html
            segment-break-transformation-rules-016.html
            segment-break-transformation-rules-017.html
            segment-break-transformation-rules-018.html
            segment-break-transformation-rules-019.html
            segment-break-transformation-rules-020.html
            segment-break-transformation-rules-021.html
            segment-break-transformation-rules-022.html
            segment-break-transformation-rules-023.html
            segment-break-transformation-rules-024.html
            segment-break-transformation-rules-025.html
            segment-break-transformation-rules-026.html
            segment-break-transformation-rules-027.html
            segment-break-transformation-rules-028.html
            segment-break-transformation-rules-029.html
            segment-break-transformation-rules-030.html
            segment-break-transformation-rules-031.html
            segment-break-transformation-rules-032.html
            segment-break-transformation-rules-033.html
            segment-break-transformation-rules-034.html
            segment-break-transformation-rules-035.html
            segment-break-transformation-rules-036.html
            segment-break-transformation-rules-037.html
            segment-break-transformation-rules-038.html
            segment-break-transformation-rules-039.html
            segment-break-transformation-rules-040.html
            segment-break-transformation-rules-041.html
            segment-break-transformation-rules-042.html
            segment-break-transformation-rules-043.html
            segment-break-transformation-rules-044.html
            segment-break-transformation-rules-045.html
            segment-break-transformation-rules-046.html
            segment-break-transformation-rules-047.html
            segment-break-transformation-rules-048.html
            segment-break-transformation-rules-049.html
          </wpt>
        <li>Otherwise, if the <a>writing system</a> of the <a>segment break</a>
          is <a for=writing-system>Chinese</a>, <a for=writing-system>Japanese</a>, or Yi,
          and the character before or after the segment break
          is punctuation or a symbol (Unicode <a>general category</a> P* or S*)
          and has an <a>East Asian Width property</a> of <code>Ambiguous</code>,
          and the character on the other side of the segment break is
          <code>Fullwidth</code>, <code>Wide</code>, or <code>Halfwidth</code>,
          and not Hangul,
          then the segment break is removed.

          <wpt>
            writing-system/writing-system-segment-break-001.html
          </wpt>
        <li>Otherwise, the segment break is converted to a space (U+0020).
      </ul>

      <p>
        For this purpose,
        Emoji (Unicode property <code>Emoji</code>)
        with an <a>East Asian Width property</a> of
        <code>Wide</code> or <code>Neutral</code>
        are treated as having an <a>East Asian Width property</a> of
        <code>Ambiguous</code>.

      <p class="note">Note: The white space processing rules have already
        removed any tabs and spaces after the segment break before these checks
        take place.</p>

      <div class="example">
        The purpose of the segment break transformation rules
        (and white space collapsing in general)
        is to “unbreak” text that has been
        <a href="#white-space-processing">broken into segments</a>
        to make the document source code easier to work with.
        In languages that use word separators, such as English and Korean,
        “unbreaking” a line requires joining the two lines with a space.

        <figure>
          <pre>
            Here is an English paragraph
            that is broken into multiple lines
            in the source code so that it can
            more easily read in a text editor.
          </pre>
          <p>Here is an English paragraph that is broken into multiple lines in the source code so that it can be more easily read in a text editor.</p>
          <figcaption>
            Eliminating a line break in English requires maintaining a space in its place.
          </figcaption>
        </figure>

        In languages that have no word separators, such as Chinese,
        “unbreaking” a line requires joining the two lines with no intervening space.

        <figure>
          <pre>
            这个段落是呢么长，
            在一行写不行。最好
            用三行写。
          </pre>
          <p>这个段落是呢么长，在一行不行。最好用三行写。</p>
          <figcaption>
            Eliminating a line break in Chinese requires eliminating any intervening white space.
          </figcaption>
        </figure>

        The segment break transformation rules thus use adjacent context
        to either transform the segment break into a space
        or eliminate it entirely.
      </div>

      <p class="feedback issue">Comments on how well these rules would work in practice would
        be very much appreciated, particularly from people who work with
        Thai and similar scripts.
        Note that browser implementations do not currently follow these rules consistently
        (although IE does in some cases transform the break,
        and Firefox follows the first two bullet points).</p>

    <h4 id="white-space-phase-2">Phase II: Trimming and Positioning</h4>

    <p>As each line is laid out,</p>
    <ol>
      <li>A sequence of collapsible spaces at the beginning of a line
        (ignoring any intervening <a>inline box</a> boundaries)
        is removed.

        <wpt>
          white-space/line-edge-white-space-collapse-002.html
        </wpt>
        <wpt pathprefix="/css/CSS2/text/">
          white-space-collapsing-003.xht
          white-space-collapsing-bidi-003.xht
          white-space-normal-001.xht
          white-space-normal-002.xht
          white-space-processing-037.xht
          white-space-processing-038.xht
          white-space-processing-040.xht
          white-space-processing-041.xht
        </wpt>
      <li>If the tab size is zero, tabs are not rendered.
        Otherwise, each tab is rendered as a horizontal shift
        that lines up the start edge of the next glyph with the next <a>tab stop</a>.
        If this distance is less than 0.5<a href="https://www.w3.org/TR/css-values-3/#ch">ch</a>,
        then the subsequent <a>tab stop</a> is used instead.
        <dfn lt="tab stop">Tab stops</dfn> occur at points that are multiples of the tab size
        from the block's starting content edge.
        The tab size is given by the 'tab-size' property.

        <wpt>
          white-space/tab-stop-threshold-001.html
          white-space/tab-stop-threshold-002.html
          white-space/tab-stop-threshold-003.html
          white-space/tab-stop-threshold-004.html
          white-space/tab-stop-threshold-005.html
          white-space/tab-stop-threshold-006.html
          tab-size/tab-min-rendered-width-1.html
          tab-size/tab-size-integer-003.html
        </wpt>
        <wpt pathprefix="/css/CSS2/text/">
          white-space-processing-042.xht
        </wpt>

        Note: See [[UAX9]] for <a href="http://unicode.org/reports/tr9/#L1">rules on how U+0009 tabulation interacts with bidi</a>.

      <li>A sequence at the end of a line
        (ignoring any intervening <a>inline box</a> boundaries)
        of <a>collapsible</a> spaces (U+0020)
        and/or ideographic spaces (U+3000) whose 'white-space' value collapses spaces
        is removed.

        <wpt>
          white-space/line-edge-white-space-collapse-001.html
          white-space/pre-float-001.html
          white-space/pre-wrap-float-001.html
          white-space/trailing-ideographic-space-001.html
          white-space/trailing-ideographic-space-002.html
          white-space/trailing-space-before-br-001.html
        </wpt>
        <wpt pathprefix="/css/CSS2/text/">
          white-space-collapsing-003.xht
          white-space-collapsing-bidi-003.xht
          white-space-normal-001.xht
          white-space-normal-002.xht
          white-space-processing-043.xht
          white-space-processing-044.xht
          white-space-processing-045.xht
          white-space-processing-046.xht
          white-space-processing-047.xht
        </wpt>
      <li>If there remains any sequence of <a>white space</a>
        and/or ideographic spaces (U+3000)
        at the end of a line:
        <ul>
          <li>If 'white-space' is set to ''pre-wrap'',
             the UA must <a>hang</a> this sequence
             if it does not otherwise fit prior to justification.
             It may also visually collapse the character advance widths
             of any that would otherwise overflow.

             <wpt>
               white-space/pre-wrap-001.html
               white-space/pre-wrap-002.html
               white-space/pre-wrap-003.html
               white-space/pre-wrap-004.html
               white-space/pre-wrap-005.html
               white-space/pre-wrap-006.html
               white-space/pre-wrap-007.html
               white-space/pre-wrap-011.html
               white-space/pre-wrap-012.html
               white-space/pre-wrap-013.html
               white-space/pre-wrap-014.html
               white-space/textarea-pre-wrap-001.html
               white-space/textarea-pre-wrap-002.html
               white-space/textarea-pre-wrap-003.html
               white-space/textarea-pre-wrap-004.html
               white-space/textarea-pre-wrap-005.html
               white-space/textarea-pre-wrap-006.html
               white-space/textarea-pre-wrap-007.html
               white-space/textarea-pre-wrap-011.html
               white-space/textarea-pre-wrap-012.html
               white-space/textarea-pre-wrap-013.html
               white-space/textarea-pre-wrap-014.html
               white-space/trailing-ideographic-space-003.html
               white-space/trailing-ideographic-space-004.html
               white-space/white-space-pre-wrap-trailing-spaces-001.html
               white-space/white-space-pre-wrap-trailing-spaces-002.html
               white-space/white-space-pre-wrap-trailing-spaces-003.html
               white-space/white-space-intrinsic-size-003.html
               white-space/white-space-intrinsic-size-004.html
             </wpt>

             Note: Hanging the white space rather than collapsing it
             allows users to see the space when selecting or editing text.
          <li>If 'white-space' is set to ''break-spaces'',
             hanging or collapsing the advance width of spaces
             at the end of the line is not allowed;
             those that overflow must <a>wrap</a> to the next line.

             <wpt>
               white-space/break-spaces-001.html
               white-space/break-spaces-005.html
               white-space/textarea-break-spaces-001.html
             </wpt>
        </ul>

    </ol>

    <div class=example>
      This example illustrates the consequence of [=hanging=] white space
      at the end of the line
      on text alignment.
      <pre><code class=lang-css>
      p {
        white-space: pre-wrap;
        text-align: end;
        width: 20ch;
        border: solid 1px;
      }</code></pre>
      <pre><code class=lang-markup>
      &lt;p>Lorem ipsum      &lt;/p>
      </code></pre>

      As the preserved spaces at the end of the line must [=hang=],
      they are not considered when placing the rest of the line during text alignment.
      When aligning towards the end,
      this means any such spaces will overflow,
      and will not prevent the rest of the line's content from being flush with the edge of the line.
      The sample above would therefore be rendered as follows:
      <pre class=output style="width: 20ch; border: solid 1px; text-align: end;">
      Lorem ipsum
      </pre>
    </div>

  <h3 id="tab-size-property" caniuse="css3-tabsize" oldids="tab-size">
    Tab Character Size: the 'tab-size' property</h3>

    <pre class="propdef">
    Name: tab-size
    Value: <<number>> | <<length>>
    Initial: 8
    Applies to: block containers
    Inherited: yes
    Computed value: the specified number or absolute length
    Animation type: by computed value type
    Canonical order: n/a
    </pre>

    <wpt>
      tab-size/tab-size-integer-001.html
      tab-size/tab-size-inheritance-001.html
      inheritance.html
      parsing/tab-size-valid.html
      parsing/tab-size-invalid.html
    </wpt>

    <p>This property determines the tab size used to render preserved tab characters (U+0009).
      A <<number>> represents the measure as a multiple of the space character's advance width (U+0020)
      including its associated 'letter-spacing' and 'word-spacing'.
      Negative values are not allowed.

      <wpt>
        tab-size/tab-size-integer-001.html
        tab-size/tab-size-integer-002.html
        tab-size/tab-size-integer-003.html
        tab-size/tab-size-length-001.html
        tab-size/tab-size-length-002.html
        tab-size/tab-size-percent-001.html
        tab-size/tab-min-rendered-width-1.html
        tab-size/tab-size-spacing-001.html
        white-space/tab-stop-threshold-001.html
        white-space/tab-stop-threshold-002.html
        white-space/tab-stop-threshold-003.html
        white-space/tab-stop-threshold-004.html
        white-space/tab-stop-threshold-005.html
        white-space/tab-stop-threshold-006.html
      </wpt>
      <wpt pathprefix="/css/CSS2/text/">
        white-space-processing-042.xht
      </wpt>

<h2 id="line-breaking">
  Line Breaking and Word Boundaries</h2>

  <p>When inline-level content is laid out into lines, it is broken across line boxes.
    Such a break is called a <dfn>line break</dfn>.
    When a line is broken due to explicit line-breaking controls
    (such as a <a>preserved</a> newline character),
    or due to the start or end of a block,
    it is a <dfn>forced line break</dfn>.
    When a line is broken due to content <dfn lt="wrapping|wrap">wrapping</dfn>
    (i.e. when the UA creates unforced line breaks in order to fit the content within the measure),
    it is a <dfn>soft wrap break</dfn>.
    The process of breaking inline-level content into lines is called <dfn export lt="line breaking process | line breaking">line breaking</dfn>.

  <p>Wrapping is only performed at an allowed break point,
    called a <dfn export>soft wrap opportunity</dfn>.
    When wrapping is enabled (see 'white-space'),
    the UA must minimize the amount of content overflowing a line
    by wrapping the line at a <a>soft wrap opportunity</a>,
    if one exists.

  <p>In most writing systems,
    in the absence of hyphenation a <a>soft wrap opportunity</a> occurs only at word boundaries.
    Many such systems use spaces or punctuation to explicitly separate words,
    and <a>soft wrap opportunities</a> can be identified by these characters.
    Scripts such as Thai, Lao, and Khmer, however,
    do not use spaces or punctuation to separate words.
    Although the zero width space (U+200B) can be used as an explicit word delimiter in these scripts,
    this practice is not common.
    As a result, a lexical resource is needed to correctly identify <a>soft wrap opportunities</a> in such texts.

  <p>In some other writing systems,
    <a>soft wrap opportunities</a> are based on orthographic syllable boundaries,
    not word boundaries.
    Some of these systems, such as Javanese and Balinese,
    are similar to Thai and Lao in that they
    require analysis of the text to find breaking opportunities.
    In others such as Chinese (as well as Japanese, Yi, and sometimes also Korean),
    each syllable tends to correspond to a single <a>typographic letter unit</a>,
    and thus line breaking conventions allow the line to break
    anywhere <em>except</em> between certain character combinations.
    Additionally the level of strictness in these restrictions
    varies with the typesetting style.

    <wpt>
      i18n/css3-text-line-break-baspglwj-003.html
      i18n/css3-text-line-break-baspglwj-004.html
      i18n/css3-text-line-break-baspglwj-005.html
      i18n/css3-text-line-break-baspglwj-006.html
      i18n/css3-text-line-break-baspglwj-007.html
      i18n/css3-text-line-break-baspglwj-008.html
      i18n/css3-text-line-break-baspglwj-009.html
      i18n/css3-text-line-break-baspglwj-010.html
      i18n/css3-text-line-break-baspglwj-011.html
      i18n/css3-text-line-break-baspglwj-012.html
      i18n/css3-text-line-break-baspglwj-014.html
      i18n/css3-text-line-break-baspglwj-015.html
      i18n/css3-text-line-break-baspglwj-016.html
      i18n/css3-text-line-break-baspglwj-017.html
      i18n/css3-text-line-break-baspglwj-018.html
      i18n/css3-text-line-break-baspglwj-019.html
      i18n/css3-text-line-break-baspglwj-020.html
      i18n/css3-text-line-break-baspglwj-021.html
      i18n/css3-text-line-break-baspglwj-022.html
      i18n/css3-text-line-break-baspglwj-023.html
      i18n/css3-text-line-break-baspglwj-024.html
      i18n/css3-text-line-break-baspglwj-025.html
      i18n/css3-text-line-break-baspglwj-026.html
      i18n/css3-text-line-break-baspglwj-030.html
      i18n/css3-text-line-break-baspglwj-031.html
      i18n/css3-text-line-break-baspglwj-032.html
      i18n/css3-text-line-break-baspglwj-033.html
      i18n/css3-text-line-break-baspglwj-034.html
      i18n/css3-text-line-break-baspglwj-035.html
      i18n/css3-text-line-break-baspglwj-036.html
      i18n/css3-text-line-break-baspglwj-037.html
      i18n/css3-text-line-break-baspglwj-038.html
      i18n/css3-text-line-break-baspglwj-039.html
      i18n/css3-text-line-break-baspglwj-040.html
      i18n/css3-text-line-break-baspglwj-041.html
      i18n/css3-text-line-break-baspglwj-042.html
      i18n/css3-text-line-break-baspglwj-043.html
      i18n/css3-text-line-break-baspglwj-044.html
      i18n/css3-text-line-break-baspglwj-045.html
      i18n/css3-text-line-break-baspglwj-046.html
      i18n/css3-text-line-break-baspglwj-047.html
      i18n/css3-text-line-break-baspglwj-048.html
      i18n/css3-text-line-break-baspglwj-049.html
      i18n/css3-text-line-break-baspglwj-050.html
      i18n/css3-text-line-break-baspglwj-051.html
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      i18n/css3-text-line-break-opclns-204.html
      i18n/css3-text-line-break-opclns-205.html
      i18n/css3-text-line-break-opclns-206.html
      i18n/css3-text-line-break-opclns-207.html
      i18n/css3-text-line-break-opclns-208.html
      i18n/css3-text-line-break-opclns-209.html
      i18n/css3-text-line-break-opclns-210.html
      i18n/css3-text-line-break-opclns-211.html
      i18n/css3-text-line-break-opclns-212.html
      i18n/css3-text-line-break-opclns-213.html
      i18n/css3-text-line-break-opclns-214.html
      i18n/css3-text-line-break-opclns-215.html
      i18n/css3-text-line-break-opclns-217.html
      i18n/css3-text-line-break-opclns-218.html
      i18n/css3-text-line-break-opclns-219.html
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      i18n/css3-text-line-break-opclns-221.html
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      i18n/css3-text-line-break-opclns-226.html
    </wpt>

  <p>While CSS does not fully define where <a>soft wrap opportunities</a> occur,
    some controls are provided to distinguish common variations:

  <ul>
    <li>
      The 'line-break' property allows choosing various levels of “strictness”
      for line breaking restrictions.
    <li>
      The 'word-break' property controls what types of letters
      are glommed together to form unbreakable “words”,
      causing CJK characters to behave like non-CJK text or vice versa.
    <li>
      The 'hyphens' property controls whether automatic hyphenation
      is allowed to break words in scripts that hyphenate.
    <li>
      The 'overflow-wrap' property allows the UA to take a break anywhere
      in otherwise-unbreakable strings that would otherwise overflow.
  </ul>

  <div class="note">
    <p>Note: Further information on line breaking conventions can be found in
      [[JLREQ]] and [[JIS4051]] for Japanese,
      [[CLREQ]] and [[ZHMARK]] for Chinese, and
      in [[!UAX14]] for all scripts in Unicode.
      See also the
      <a href="https://www.w3.org/International/">Internationalization Working Group</a>’s
      <a href="https://www.w3.org/TR/typography/#blocks_paragraphs">Typography Index</a> [[TYPOGRAPHY]]
      which includes more information on additional languages.

    <p class="feedback issue">Any guidance for additional appropriate references
      would be much appreciated.
  </div>

<h3 id="line-break-details">
Line Breaking Details</h3>

  <p>When determining <a>line breaks</a>:
  <ul>
    <li>Regardless of the 'white-space' value,
      lines always break at each <a>preserved</a> forced break character:
      thus
      for all values, line-breaking behavior defined for
      the BK and NL line breaking classes in [[!UAX14]]
      must be honored.
    <li>Except where explicitly defined otherwise
      (e.g. for ''line-break: anywhere'' or ''overflow-wrap: anywhere'')
      line breaking behavior defined for
      the WJ, ZW, GL, and ZWJ line-breaking classes in [[!UAX14]]
      must be honored.

      <wpt>
        word-break/word-break-normal-001.html
        line-breaking/line-breaking-001.html
        line-breaking/line-breaking-002.html
        line-breaking/line-breaking-003.html
        line-breaking/line-breaking-004.html
        line-breaking/line-breaking-005.html
        line-breaking/line-breaking-006.html
        line-breaking/line-breaking-007.html
        line-breaking/line-breaking-008.html
        i18n/css3-text-line-break-baspglwj-001.html
        i18n/css3-text-line-break-baspglwj-002.html
        i18n/css3-text-line-break-baspglwj-120.html
        i18n/css3-text-line-break-baspglwj-121.html
        i18n/css3-text-line-break-baspglwj-122.html
        i18n/css3-text-line-break-baspglwj-123.html
        i18n/css3-text-line-break-baspglwj-124.html
        i18n/css3-text-line-break-baspglwj-125.html
        i18n/css3-text-line-break-baspglwj-126.html
        i18n/css3-text-line-break-baspglwj-127.html
        i18n/css3-text-line-break-baspglwj-128.html
        i18n/css3-text-line-break-baspglwj-130.html
        i18n/css3-text-line-break-baspglwj-131.html
      </wpt>

    <li>UAs that allow wrapping at punctuation
      other than <a>word separators</a>
      in writing systems that use them
      <em>should</em> prioritize breakpoints.
      (For example, if breaks after slashes are given a lower priority than spaces,
      the sequence “check /etc” will never break between the "/" and the "e".)
      As long as care is taken to avoid such awkward breaks,
      allowing breaks at appropriate punctuation other than <a>word separators</a>
      is recommended,
      as it results in more even-looking margins, particularly in narrow measures.
      The UA may use the width of the containing block, the text's language,
      the 'line-break' value,
      and other factors in assigning priorities:
      CSS does not define prioritization of line breaking opportunities.
      Prioritization of <a>word separators</a> is not expected,
      however,
      if ''word-break: break-all'' is specified
      (since this value explicitly requests line breaking behavior
      not based on breaking at <a>word separators</a>)--
      and is forbidden under ''line-break: anywhere''.

    <li>Out-of-flow elements
      and inline element boundaries
      do not introduce a <a>forced line break</a>
      or <a>soft wrap opportunity</a> in the flow.

      <wpt>
        line-breaking/line-breaking-012.html
        line-breaking/line-breaking-015.html
        line-breaking/line-breaking-016.html
        line-breaking/line-breaking-017.html
      </wpt>

    <li>The line breaking behavior of a replaced element or other atomic inline
      is equivalent to an ideographic character
      (Unicode linebreaking class <code>ID</code> [[!UAX14]]),
      and additionally, for Web-compatibility, introduces a <a>soft wrap opportunity</a>
      between itself and any adjacent U+00A0 NO-BREAK SPACE character.

      <wpt>
      line-breaking/line-breaking-001.html
      line-breaking/line-breaking-002.html
      line-breaking/line-breaking-003.html
      line-breaking/line-breaking-004.html
      line-breaking/line-breaking-005.html
      line-breaking/line-breaking-006.html
      line-breaking/line-breaking-007.html
      line-breaking/line-breaking-008.html
      line-breaking/line-breaking-009.html
      line-breaking/line-breaking-010.html
      line-breaking/line-breaking-011.html
      line-breaking/line-breaking-012.html
      line-breaking/line-breaking-013.html
      line-breaking/line-breaking-014.html
      line-breaking/line-breaking-atomic-001.html
      line-breaking/line-breaking-atomic-002.html
      line-breaking/line-breaking-atomic-003.html
      line-breaking/line-breaking-atomic-004.html
      line-breaking/line-breaking-atomic-005.html
      line-breaking/line-breaking-atomic-006.html
      line-breaking/line-breaking-atomic-007.html
      line-breaking/line-breaking-atomic-008.html
      line-breaking/line-breaking-ic-001.html
      line-breaking/line-breaking-ic-002.html
      line-breaking/line-breaking-ic-003.html
      line-breaking/line-breaking-replaced-001.html
      line-breaking/line-breaking-replaced-002.html
      line-breaking/line-breaking-replaced-003.html
      line-breaking/line-breaking-replaced-004.html
      line-breaking/line-breaking-replaced-005.html
      </wpt>
    <li>For <a>soft wrap opportunities</a> created by characters that disappear at the line break (e.g. U+0020 SPACE),
      properties on the box directly containing that character control the line breaking at that opportunity.
      For <a>soft wrap opportunities</a> defined by the boundary between two characters,
      the properties on nearest common ancestor of the two characters controls breaking.
      <!-- http://lists.w3.org/Archives/Public/www-style/2008Dec/0043.html -->

      <wpt>
        line-breaking/line-breaking-009.html
        line-breaking/line-breaking-010.html
        line-breaking/line-breaking-011.html
        line-breaking/line-breaking-ic-001.html
        line-breaking/line-breaking-ic-002.html
        line-breaking/line-breaking-ic-003.html
        white-space/white-space-wrap-after-nowrap-001.html
      </wpt>
    <li>For <a>soft wrap opportunities</a> before the first or after the last character of a box,
      the break occurs immediately before/after the box (at its margin edge)
      rather than breaking the box between its content edge and the content.
    <li>Line breaking in/around Ruby is defined in <a href="https://www.w3.org/TR/css-ruby-1/#line-breaks">CSS Ruby</a> [[!CSS-RUBY-1]].
  </ul>

  <h3 id="word-break-property" caniuse="word-break" oldids="word-break">
    Breaking Rules for Letters: the 'word-break' property</h3>

    <pre class="propdef">
    Name: word-break
    Value: normal | keep-all | break-all | break-word
    Initial: normal
    Applies to: <a>inline boxes</a>
    Inherited: yes
    Canonical order: n/a
    Computed value: specified keyword
    Animation type: discrete
    </pre>

    <wpt>
      inheritance.html
      parsing/word-break-invalid.html
      parsing/word-break-valid.html
    </wpt>

    <p>This property specifies <a>soft wrap opportunities</a> between letters,
      i.e. where it is “normal” and permissible to break lines of text.
      Specifically it controls whether a <a>soft wrap opportunity</a>
      generally exists
      between adjacent <a>typographic letter units</a>
      (and/or non-<a>letter</a> <a>typographic character units</a>
      belonging to the
      <code>NU</code>, <code>AL</code>, <code>AI</code>, or <code>ID</code>
      Unicode line breaking classes [[!UAX14]]).
      It does not affect rules governing the <a>soft wrap opportunities</a>
      created by spaces (including U+3000 IDEOGRAPHIC SPACE) and around punctuation.
      (See 'line-break' for controls affecting punctuation and small kana.)

      <wpt>
        word-break/word-break-break-all-010.html
        word-break/word-break-break-all-020.html
        word-break/word-break-keep-all-005.html
        word-break/word-break-keep-all-006.html
        word-break/word-break-break-all-012.html
        word-break/word-break-break-all-013.html
        word-break/word-break-break-all-015.html
        white-space/break-spaces-008.html
      </wpt>

    <div class="example">
      <p>For example, in some styles of CJK typesetting, English words are allowed
        to break between any two letters, rather than only at spaces or hyphenation points;
        this can be enabled with ''word-break:break-all''.

      <div class="figure">
        <img src="images/break-all.png" alt="A snippet of Japanese text with English in it. The word 'caption' is broken into 'capt' and 'ion' across two lines.">
        <p class="caption">An example of English text embedded in Japanese
          being broken at an arbitrary point in the word.
      </div>

      <p>As another example, Korean has two styles of line-breaking:
        between any two Korean syllables (''word-break: normal'')
        or, like English, mainly at spaces (''word-break: keep-all'').
      <pre>
        각 줄의 마지막에 한글이 올 때 줄 나눔 <strong>기
        준을</strong> “글자” 또는 “어절” 단위로 한다.</pre>
      <pre>
        각 줄의 마지막에 한글이 올 때 줄 나눔
        <strong>기준을</strong> “글자” 또는 “어절” 단위로 한다.</pre>
    </div>

    <p class="note">
      Note: To enable additional break opportunities only in the case of overflow,
      see 'overflow-wrap'.

    <p>Values have the following meanings:</p>

    <dl dfn-for=word-break dfn-type=value>
      <dt><dfn>normal</dfn></dt>
      <dd>Words break according to their customary rules,
       as described <a href="#line-breaking">above</a>.
       Korean, which commonly exhibits two different behaviors,
       allows breaks between any two consecutive Hangul/Hanja.

       <wpt>
         word-break/word-break-normal-ar-000.html
         word-break/word-break-normal-bo-000.html
         word-break/word-break-normal-en-000.html
         word-break/word-break-normal-hi-000.html
         word-break/word-break-normal-ja-000.html
         word-break/word-break-normal-ja-001.html
         word-break/word-break-normal-ja-002.html
         word-break/word-break-normal-ja-004.html
         word-break/word-break-normal-km-000.html
         word-break/word-break-normal-ko-000.html
         word-break/word-break-normal-lo-000.html
         word-break/word-break-normal-my-000.html
         word-break/word-break-normal-tdd-000.html
         word-break/word-break-normal-th-000.html
         word-break/word-break-normal-zh-000.html
       </wpt>

      <dt><dfn>break-all</dfn></dt>
      <dd>Breaking is allowed within “words”:
        specifically,
        in addition to <a>soft wrap opportunities</a> allowed for ''word-break/normal'',
        any <a>typographic character units</a> resolving to the
        <code>NU</code> (“numeric”), <code>AL</code> (“alphabetic”), or <code>SA</code> (“Southeast Asian”)
        line breaking classes [[!UAX14]]
        are instead treated as <code>ID</code> (“ideographic characters”)
        for the purpose of line-breaking.
        Hyphenation is not applied.
        This option is used mostly in a context where
        the text consists predominantly of CJK characters
        with only short non-CJK excerpts,
        and it is desired that the text be better distributed on each line.

        <wpt>
          word-break/word-break-break-all-000.html
          word-break/word-break-break-all-001.html
          word-break/word-break-break-all-002.html
          word-break/word-break-break-all-003.html
          word-break/word-break-break-all-005.html
          word-break/word-break-break-all-006.html
          word-break/word-break-break-all-012.html
          word-break/word-break-break-all-013.html
          word-break/word-break-break-all-014.html
          word-break/word-break-break-all-015.html
          white-space/break-spaces-006.html
          white-space/break-spaces-008.html
        </wpt>

        Note: This value does not affect
        whether there are <a>soft wrap opportunities</a>
        around punctuation characters.
        To allow breaks anywhere, see ''line-break: anywhere''.

      <dt><dfn>keep-all</dfn></dt>
      <dd>Breaking is forbidden within “words”:
        implicit <a>soft wrap opportunities</a> between <a>typographic letter units</a>
        (or other <a>typographic character units</a>
        belonging to the
        <code>NU</code>, <code>AL</code>, <code>AI</code>, or <code>ID</code>
        Unicode line breaking classes [[!UAX14]])
        are suppressed,
        i.e. breaks are prohibited between pairs of such characters
        (regardless of 'line-break' settings other than ''line-break/anywhere'')
        except where opportunities exist due to dictionary-based breaking.
        Otherwise this option is equivalent to ''word-break/normal''.
        In this style, sequences of CJK characters do not break.

        <wpt>
          word-break/word-break-keep-all-000.html
          word-break/word-break-keep-all-001.html
          word-break/word-break-keep-all-002.html
          word-break/word-break-keep-all-003.html
        </wpt>

        <p class=note>Note: This is the other common behavior for Korean (which uses spaces between words),
        and is also useful for mixed-script text where CJK snippets are mixed
        into another language that uses spaces for separation.
    </dl>

    <p>Symbols that line-break the same way as letters of a particular category
    are affected the same way as those letters.

     <div class="example">
      <p>Here's a mixed-script sample text:
      <pre style="white-space: pre-wrap">
        这是一些汉字 and some Latin <bdi dir=rtl>و کمی خط عربی</bdi> และตัวอย่างการเขียนภาษาไทย
      </pre>
      <p>The break-points are determined as follows (indicated by &lsquo;&middot;&rsquo;):
      <dl>
        <dt>''word-break: normal''</dt>
        <dd>
          <pre style="white-space: pre-wrap">
            这·是·一·些·汉·字·and·some·Latin·<bdi dir=rtl>و·کمی·خط·عربی</bdi>·และ·ตัวอย่าง·การเขียน·ภาษาไทย
          </pre>
        <dt>''word-break: break-all''</dt>
        <dd>
          <pre style="white-space: pre-wrap">
            这·是·一·些·汉·字·a·n·d·s·o·m·e·L·a·t·i·n·<bdi dir=rtl>و·ﮐ·ﻤ·ﻰ·ﺧ·ﻁ·ﻋ·ﺮ·ﺑ·ﻰ</bdi>·แ·ล·ะ·ตั·ว·อ·ย่·า·ง·ก·า·ร·เ·ขี·ย·น·ภ·า·ษ·า·ไ·ท·ย
          </pre>
        <dt>''word-break: keep-all''</dt>
        <dd>
          <pre style="white-space: pre-wrap">
            这是一些汉字·and·some·Latin·<bdi dir=rtl>و·کمی·خط·عربی</bdi>·และ·ตัวอย่าง·การเขียน·ภาษาไทย
          </pre>
      </dl>
    </div>

    <div class="example" id=jp-title-break>
      <style>
      #jp-title-break td samp,
      #jp-title-break td pre {
	font-size: 1.5em;
        width: 9em;
        line-height: 2;
        padding: 0.5em 1em;
        display: block;
        margin: auto;
        border: solid gray 1px;
        background: white;
      }
      </style>
      <p>Japanese is usually typeset allowing line breaks within words.
      However, it is sometimes preferred to suppress these wrapping opportunities
      and to only allow wrapping at the end of certain sentence fragments.
      This is most commonly done in very short pieces of text,
      such as headings and table or figure captions.

      This can be achieved by marking the allowed wrapping points
      with <{wbr}> or U+200B ZERO WIDTH SPACE,
      and suppressing the other ones using ''word-break: keep-all''.

      For instance, the following markup can produce either of the renderings below,
      depending on the value of the 'word-break' property:
      <pre><code highlight=markup>
      &lt;h1>窓ぎわの&lt;wbr>トットちゃん&lt;/h1>
      </code></pre>

      <table class=data>
      <colgroup span=1></colgroup>
      <colgroup span=2></colgroup>
      <thead>
      <tr>
        <td>
        <th><code highlight=css>h1 { word-break: normal }</code>
        <th><code highlight=css>h1 { word-break: keep-all }</code>
      <tbody>
      <tr>
        <th scope=row>Expected rendering
        <td>
          <pre lang=ja>
	  窓ぎわのトットちゃ
	  ん</pre>
        <td>
          <pre lang=ja>
	  窓ぎわの
	  トットちゃん</pre>
      <tr>
        <th scope=row>Result in your browser
        <td>
          <samp lang=ja>
          窓ぎわの<wbr>トットちゃん
          </samp>
        <td>
          <samp style="word-break:keep-all" lang=ja>
          窓ぎわの<wbr>トットちゃん
          </samp>
      </table>
    </div>

    <p>When shaping scripts such as Arabic
      are allowed to break within words due to ''word-break/break-all''
      the characters must still be shaped
      as if the word were <a href="#word-break-shaping">not broken</a>
      (see [[#word-break-shaping]]).

      <wpt>
        word-break/word-break-break-all-004.html
      </wpt>

    <p>For compatibility with legacy content,
      the 'word-break' property also supports a deprecated <dfn value for=word-break>break-word</dfn> keyword.
      When specified, this has the same effect as
      ''word-break: normal'' and ''overflow-wrap: anywhere'',
      regardless of the actual value of the 'overflow-wrap' property.
      <!-- This is officially sad -->

      <wpt>
        white-space/pre-wrap-008.html
        white-space/pre-wrap-016.html
        word-break/word-break-break-word-overflow-wrap-interactions.html
        white-space/break-spaces-003.html
        white-space/break-spaces-004.html
        white-space/break-spaces-008.html
      </wpt>

  <h3 id="line-break-property">
    Line Breaking Strictness: the 'line-break' property</h3>

    <pre class="propdef">
    Name: line-break
    Value: auto | loose | normal | strict | anywhere
    Initial: auto
    Applies to: <a>inline boxes</a>
    Inherited: yes
    Canonical order: n/a
    Computed value: specified keyword
    Animation type: discrete
    </pre>

    <wpt>
      inheritance.html
      parsing/line-break-valid.html
      parsing/line-break-invalid.html
    </wpt>

    <p>This property specifies the strictness of line-breaking rules applied
      within an element:
      especially how <a>wrapping</a> interacts with punctuation and symbols.
      Values have the following meanings:</p>

    <dl dfn-for=line-break dfn-type=value>
      <dt><dfn>auto</dfn></dt>
      <dd>The UA determines the set of line-breaking restrictions to use,
        and it may vary the restrictions based on the length of the line; e.g.,
        use a less restrictive set of line-break rules for short lines.
      <dt><dfn>loose</dfn></dt>
      <dd>Breaks text using the least restrictive set of line-breaking
        rules. Typically used for short lines, such as in newspapers.</dd>
      <dt><dfn>normal</dfn></dt>
      <dd>Breaks text using the most common set of line-breaking rules.</dd>
      <dt><dfn>strict</dfn></dt>
      <dd>Breaks text using the most stringent set of line-breaking
        rules.</dd>
      <dt><dfn>anywhere</dfn></dt>
      <dd>There is a <a>soft wrap opportunity</a> around every <a>typographic character unit</a>,
      including around any punctuation character or [=preserved white spaces=],
      or in the middle of words,
      disregarding any prohibition against line breaks,
      even those introduced by characters with the GL, WJ, or ZWJ character class (see [[UAX14]])
      or mandated by the 'word-break' property.
      The different wrapping opportunities must not be prioritized.
      Hyphenation is not applied.

      <wpt>
        line-break/line-break-anywhere-001.html
        line-break/line-break-anywhere-002.html
        line-break/line-break-shaping-001.html
      </wpt>

      Note: This value triggers the line breaking rules typically seen in terminals.</dd>

      <div class=note>
        Note: ''line-break/anywhere'' only allows [=preserved white spaces=] at the end of the line
        to be wrapped to the next line when 'white-space' is set to ''white-space/break-spaces'',
        because in other cases:
        * [=preserved white space=] at the end/start of the line is discarded (''white-space/normal'', ''white-space/pre-line'')
        * wrapping is forbidden altoghether (''nowrap'', ''pre'')
        * the spaces [=hang=] (''pre-wrap'').

        When it does have an effect on [=preserved white space=],
        with ''white-space: break-spaces'',
        it allows breaking before the first space of a sequence,
        which ''break-spaces'' on its own does not.
      </div>
    </dl>

    <p class="feedback issue">
      The rules here are following guidelines from <a href="https://www.w3.org/TR/klreq/#line-break">KLREQ</a> for Korean,
      which don't allow the Chinese/Japanese-specific breaks.
      However, the resulting behavior could use some review and feedback to make sure they are correct,
      particularly when “word basis” breaking is used (''word-break: keep-all'') in Korean.

    <p>CSS distinguishes between four levels of strictness in the rules for
      text wrapping.
      The precise set of rules in effect for each of ''line-break/loose'', ''line-break/normal'', and ''line-break/strict'' is up to the UA
      and should follow language conventions.
      However, this specification does require that:</p>

    <ul>
      <li>
        The following breaks are forbidden in ''strict'' line breaking
        and allowed in ''line-break/normal'' and ''loose'':
        <ul>
          <li>breaks before Japanese small kana or the Katakana-Hiragana prolonged sound mark:
            i.e. characters with the Unicode Line Break property <code>CJ</code>.
            (See <a href="http://www.unicode.org/Public/UNIDATA/LineBreak.txt">LineBreak.txt</a> in [[!UNICODE]].)

            <wpt>
              line-break/line-break-loose-011.xht
              line-break/line-break-loose-012.xht
              line-break/line-break-normal-011.xht
              line-break/line-break-normal-012.xht
              line-break/line-break-strict-011.xht
              line-break/line-break-strict-012.xht
              i18n/ja/css-text-line-break-ja-cj-loose.html
              i18n/ja/css-text-line-break-ja-cj-normal.html
              i18n/ja/css-text-line-break-ja-cj-strict.html
            </wpt>
        </ul>
      <li>
        The following breaks are allowed for ''line-break/normal'' and ''loose'' line breaking
        if the <a>writing system</a> is <a for=writing-system>Chinese</a> or <a for=writing-system>Japanese</a>,
        and are otherwise forbidden:
        <ul>
          <li>breaks before hyphens:<br>
            &#x2010;&nbsp;U+2010,  &#x2013;&nbsp;U+2013,  &#x301C;&nbsp;U+301C,
            &#x30A0;&nbsp;U+30A0

            <wpt>
              line-break/line-break-loose-013.xht
              line-break/line-break-normal-013.xht
              line-break/line-break-strict-013.xht
              i18n/ja/css-text-line-break-ja-hyphens-loose.html
              i18n/ja/css-text-line-break-ja-hyphens-normal.html
              i18n/ja/css-text-line-break-ja-hyphens-strict.html
              i18n/zh/css-text-line-break-zh-hyphens-loose.html
              i18n/zh/css-text-line-break-zh-hyphens-normal.html
              i18n/zh/css-text-line-break-zh-hyphens-strict.html
              writing-system/writing-system-line-break-001.html
            </wpt>
        </ul>
      <li>
        The following breaks are forbidden for ''line-break/normal'' and ''strict'' line breaking
        and allowed in ''loose'':
        <ul>
          <li>breaks before iteration marks:<br>
            &#x3005;&nbsp;U+3005,  &#x303B;&nbsp;U+303B,  &#x309D;&nbsp;U+309D,
            &#x309E;&nbsp;U+309E,  &#x30FD;&nbsp;U+30FD,  &#x30FE;&nbsp;U+30FE

            <wpt>
              line-break/line-break-loose-014.xht
              line-break/line-break-normal-014.xht
              line-break/line-break-strict-014.xht
              i18n/ja/css-text-line-break-ja-iteration-loose.html
              i18n/ja/css-text-line-break-ja-iteration-normal.html
              i18n/ja/css-text-line-break-ja-iteration-strict.html
              i18n/zh/css-text-line-break-zh-iteration-loose.html
              i18n/zh/css-text-line-break-zh-iteration-normal.html
              i18n/zh/css-text-line-break-zh-iteration-strict.html
            </wpt>
          <li>breaks between inseparable characters
            such as &#x2025;&nbsp;U+2025,  &#x2026;&nbsp;U+2026
            i.e. characters with the Unicode Line Break property <code>IN</code>.
            (See <a href="http://www.unicode.org/Public/UNIDATA/LineBreak.txt">LineBreak.txt</a> in [[!UNICODE]].)

            <wpt>
              line-break/line-break-loose-015.xht
              line-break/line-break-normal-015.xht
              line-break/line-break-strict-015.xht
              i18n/ja/css-text-line-break-ja-in-loose.html
              i18n/ja/css-text-line-break-ja-in-normal.html
              i18n/ja/css-text-line-break-ja-in-strict.html
              i18n/zh/css-text-line-break-zh-in-loose.html
              i18n/zh/css-text-line-break-zh-in-normal.html
              i18n/zh/css-text-line-break-zh-in-strict.html
            </wpt>
        </ul>
      <li>
        The following breaks are allowed for ''loose''
        if the <a>writing system</a> is <a for=writing-system>Chinese</a> or <a for=writing-system>Japanese</a>
        and are otherwise forbidden:
        <ul>
          <li>breaks before certain centered punctuation marks:<br>
            &#x30FB;&nbsp;U+30FB,
            &#xFF1A;&nbsp;U+FF1A,  &#xFF1B;&nbsp;U+FF1B,  &#xFF65;&nbsp;U+FF65,
            &#x203C;&nbsp;U+203C,
            &#x2047;&nbsp;U+2047,  &#x2048;&nbsp;U+2048,  &#x2049;&nbsp;U+2049,
            &#xFF01;&nbsp;U+FF01,  &#xFF1F;&nbsp;U+FF1F

            <wpt>
              line-break/line-break-loose-016a.xht
              line-break/line-break-loose-016b.xht
              line-break/line-break-normal-016a.xht
              line-break/line-break-normal-016b.xht
              line-break/line-break-strict-016a.xht
              line-break/line-break-strict-016b.xht
              i18n/ja/css-text-line-break-ja-cpm-loose.html
              i18n/ja/css-text-line-break-ja-cpm-normal.html
              i18n/ja/css-text-line-break-ja-cpm-strict.html
              i18n/zh/css-text-line-break-zh-cpm-loose.html
              i18n/zh/css-text-line-break-zh-cpm-normal.html
              i18n/zh/css-text-line-break-zh-cpm-strict.html
              writing-system/writing-system-line-break-002.html
            </wpt>
          <li>breaks before suffixes:<br>
            Characters with the Unicode Line Break property <code>PO</code>
            and the <a>East Asian Width property</a> [[!UAX11]]
            <code>Ambiguous</code>, <code>Fullwidth</code>, or <code>Wide</code>.

            <wpt>
              line-break/line-break-loose-017a.xht
              line-break/line-break-loose-017b.xht
              line-break/line-break-normal-017a.xht
              line-break/line-break-normal-017b.xht
              line-break/line-break-strict-017a.xht
              line-break/line-break-strict-017b.xht
              i18n/ja/css-text-line-break-ja-po-loose.html
              i18n/ja/css-text-line-break-ja-po-normal.html
              i18n/ja/css-text-line-break-ja-po-strict.html
              i18n/zh/css-text-line-break-zh-po-loose.html
              i18n/zh/css-text-line-break-zh-po-normal.html
              i18n/zh/css-text-line-break-zh-po-strict.html
            </wpt>
          <li>breaks after prefixes:<br>
            Characters with the Unicode Line Break property <code>PR</code>
            and the <a>East Asian Width property</a> [[!UAX11]]
            <code>Ambiguous</code>, <code>Fullwidth</code>, or <code>Wide</code>.

            <wpt>
              line-break/line-break-loose-018.xht
              line-break/line-break-normal-018.xht
              line-break/line-break-strict-018.xht
            </wpt>
        </ul>
    </ul>

    <p class="note">Note:
      The requirements listed above
      only create distinctions in CJK text.
      In an implementation that matches only the rules above,
      and no additional rules,
      'line-break' would only affect CJK code points
      unless the writing system is tagged as
      <a for=writing-system>Chinese</a> or <a for=writing-system>Japanese</a>.
      Future levels may add additional specific rules
      for other writing systems and languages
      as their requirements become known.

    <div class="example">
      As UAs can add additional distinctions
      between ''line-break/strict''/''line-break/normal''/''line-break/loose'' modes,
      these values can exhibit differences in other writing systems as well.
      For example, a UA with sufficiently-advanced Thai language processing ability
      could choose to map different levels of strictness in Thai line-breaking
      to these keywords,
      e.g. disallowing breaks within compound words in ''line-break/strict'' mode
      (e.g. breaking ตัวอย่างการเขียนภาษาไทย as ตัวอย่าง·การเขียน·ภาษาไทย)
      while allowing more breaks in ''line-break/loose''
      (ตัวอย่าง·การ·เขียน·ภาษา·ไทย).
    </div>

    <p class="note">Note: The CSSWG recognizes that in a future edition of the
      specification finer control over line breaking may be necessary to
      satisfy high-end publishing requirements.

  <h3 id="hyphenation" oldids="hyphens-property" caniuse="css-hyphens">
    Hyphenation: the 'hyphens' property</h3>

    <p><dfn id=hyphenate lt="hyphenation|hyphenate">Hyphenation</dfn>
      is the controlled splitting of words
      where they usually would not be allowed to break
      to improve the layout of paragraphs,
      typically splitting words at syllabic or morphemic boundaries,
      and visually indicating the split (usually by inserting a hyphen, U+2010).
      In some cases, hyphenation may also alter the spelling of a word.
      Regardless, hyphenation is a rendering effect only:
      it must have no effect on the underlying document content
      or on text selection or searching.

    <p>Hyphenation occurs when the line breaks at a valid
      <dfn>hyphenation opportunity</dfn>,
      which is a type of <a>soft wrap opportunity</a>
      that exists within a word where <a>hyphenation</a> is allowed.
      In CSS <a>hyphenation opportunities</a> are controlled
      with the 'hyphens' property.
      CSS Text Level 3 does not define the exact rules for <a>hyphenation</a>;
      however UAs are strongly encouraged
      to optimize their choice of break points
      and to chose language-appropriate hyphenation points.

      Note: The [=soft wrap opportunity=] introduced by
      the U+002D HYPHEN-MINUS character
      or the U+2010 HYPHEN character
      is not a [=hyphenation opportunity=],
      as no visual indication of the split is <em>created</em> when wrapping:
      these characters are visible whether the line is wrapped at that point or not.

      Hyphenation opportunities <em>are</em> considered when calculating
      <a lt="min-content size">min-content intrinsic sizes</a>.
    <!-- This is because it allows tables to hyphenate instead of overflowing,
         which is particularly important in long-word languages like German.
         https://bugzilla.mozilla.org/show_bug.cgi?id=418975 -->

    <pre class="propdef">
    Name: hyphens
    Value: none | manual | auto
    Initial: manual
    Applies to: <a>inline boxes</a>
    Inherited: yes
    Canonical order: n/a
    Computed value: specified keyword
    Animation type: discrete
    </pre>

    <wpt>
      inheritance.html
      parsing/hyphens-valid.html
      parsing/hyphens-invalid.html
    </wpt>

    <p>This property controls whether <a>hyphenation</a> is allowed to create more
      <a>soft wrap opportunities</a> within a line of text.
      Values have the following meanings:

    <dl dfn-for=hyphens dfn-type=value>
      <dt><dfn>none</dfn>
        <dd>Words are not hyphenated, even if characters inside
          the word explicitly define <a>hyphenation opportunities</a>.

          Note: This does not suppress the existing [=soft wrap opportunities=]
          introduced by always visible characters such as
          U+002D HYPHEN-MINUS
          or U+2010 HYPHEN.
      <dt><dfn>manual</dfn>
        <dd>Words are only hyphenated where there are characters inside the word
          that explicitly suggest <a>hyphenation opportunities</a>.
        <div class="example">
        <p>In Unicode, U+00AD is a conditional "soft hyphen" and U+2010 is an
          unconditional hyphen. Unicode Standard Annex #14 describes the
          <a href="http://unicode.org/reports/tr14/#SoftHyphen">role of soft hyphens in</a>
          Unicode line breaking. [[!UAX14]]
          In HTML, &amp;shy; represents the soft hyphen character,
          which suggests a hyphenation opportunity.
          <pre>ex&amp;shy;ample</pre>
        </div>
      <dt><dfn>auto</dfn>
        <dd>Words may be broken at <a>hyphenation opportunities</a>
          determined automatically by a language-appropriate hyphenation resource
          in addition to those indicated explicitly by a conditional hyphen.
          Automatic <a>hyphenation opportunities</a> within a word must be ignored
          if the word contains a conditional hyphen (&amp;shy; or U+00AD),
          in favor of the conditional hyphen(s).
          However, if, even after breaking at such opportunities,
          a portion of that word is is still too long to fit on one line,
          an automatic hyphenation opportunity may be used.

          <wpt pathprefix="/css/vendor-imports/mozilla/mozilla-central-reftests/text3/">
            hyphenation-control-1.html
          </wpt>
    </dl>

    <p>Correct automatic hyphenation requires a hyphenation resource
      appropriate to the language of the text being broken.
      The UA must therefore only automatically hyphenate text
      for which the <a>content language</a> is known
      and for which it has an appropriate hyphenation resource.

      <wpt>
        hyphens/hyphens-auto-001.html
      </wpt>

      <p>For the purpose of the 'hyphens' property,
      what constitutes a “word” is UA-dependent.
      However, inline element boundaries
      and out-of-flow elements
      must be ignored when determining word boundaries.

      <wpt>
        hyphens/hyphens-span-001.html
        hyphens/hyphens-span-002.html
        hyphens/hyphens-out-of-flow-001.html
        hyphens/hyphens-out-of-flow-002.html
      </wpt>

    <p class="advisement">
      Authors should correctly tag their content’s <a lt="content language">language</a>
      (e.g. using the HTML <code>lang</code> attribute
      or the HTTP <code>Content-Language</code> header)
      in order to obtain correct automatic hyphenation.

      The character or characters visually shown due to hyphenation
      at a [=hyphenation opportunity=] created by a conditional hyphen character (&amp;shy; or U+00AD)
      are inserted in-place,
      and styled according to any property that applies to the conditional hyphen character.

      <wpt>
        hyphens/shy-styling-001.html
      </wpt>

      <div class=example>
        <pre><code highlight=html>ex&lt;span style="color:red">&amp;shy;&lt;/span>ample</code></pre>

        <p>When the markup above is hyphenated, it is rendered as
        <span style="display: inline-block; background: white; border: solid 1px; vertical-align: middle; padding: 0 1ch;">
          ex<span style="color:red;">-</span><br>
          ample
        </span>
      </div>


    <p>When shaping scripts such as Arabic are allowed to break within words
      due to hyphenation,
      the characters must still be shaped
      as if the word were <a href="#word-break-shaping">not broken</a>
      (see [[#word-break-shaping]]).

      <wpt>
        hyphens/hyphens-shaping-001.html
        hyphens/hyphens-shaping-002.html
      </wpt>

    <div class="example">
      <p>For example, if the Uyghur word &ldquo;داميدى&rdquo;
      were hyphenated, it would appear as
      <img src="images/uyghur-hyphenate-joined.png"
           alt="[isolated DAL + isolated ALEF + initial MEEM + medial YEH + hyphen + line-break + final DAL + isolated ALEF MAKSURA]">
      not as
      <img src="images/uyghur-hyphenate-unjoined.png"
           alt="[isolated DAL + isolated ALEF + initial MEEM + final YEH + hyphen + line-break + isolated DAL + isolated ALEF MAKSURA]">
    </div>

  <h3 id="overflow-wrap-property" caniuse="wordwrap" oldids="overflow-wrap">
    Overflow Wrapping: the 'overflow-wrap'/'word-wrap' property</h3>

  <pre class="propdef">
  Name: overflow-wrap, word-wrap
  Value: normal | break-word | anywhere
  Initial: normal
  Applies to: <a>inline boxes</a>
  Inherited: yes
  Canonical order: n/a
  Computed value: specified keyword
  Animation type: discrete
  </pre>

  <wpt>
    inheritance.html
    parsing/overflow-wrap-invalid.html
    parsing/overflow-wrap-valid.html
    parsing/word-wrap-invalid.html
    parsing/word-wrap-valid.html
    overflow-wrap/overflow-wrap-anywhere-span-001.html
    overflow-wrap/overflow-wrap-anywhere-span-002.html
    overflow-wrap/overflow-wrap-break-word-span-001.html
    overflow-wrap/overflow-wrap-break-word-span-002.html
  </wpt>

    <p>This property specifies whether the UA may break at otherwise disallowed points within a line
      to prevent overflow,
      when an otherwise-unbreakable string is too long to fit within the line box.
      It only has an effect when
      'white-space' allows <a>wrapping</a>. Possible values:</p>

      <wpt>
        overflow-wrap/overflow-wrap-002.html
      </wpt>

    <dl dfn-for=overflow-wrap dfn-type=value>
    <dt><dfn>normal</dfn></dt>
    <dd>Lines may break only at allowed break points. However, the restrictions
      introduced by ''word-break: keep-all'' may be relaxed to match ''word-break: normal''
      if there are no otherwise-acceptable break points in the line.</dd>

      <wpt>
        overflow-wrap/overflow-wrap-004.html
        overflow-wrap/overflow-wrap-normal-keep-all-001.html
      </wpt>

    <dt><dfn>anywhere</dfn>
    <dd>An otherwise unbreakable sequence of <a>characters</a>
      may be broken at an arbitrary point if
      there are no otherwise-acceptable break points in the line.
      Shaping characters are still shaped as if the word were not
      broken, and grapheme clusters must stay together as one unit.
      No hyphenation character is inserted at the break point.
      <a>Soft wrap opportunities</a> introduced by ''overflow-wrap/anywhere''
      <em>are considered</em>
      when calculating <a lt="min-content size">min-content intrinsic sizes</a>.

      <wpt>
        overflow-wrap/overflow-wrap-min-content-size-001.html
        overflow-wrap/overflow-wrap-min-content-size-002.html
        overflow-wrap/overflow-wrap-min-content-size-003.html
	overflow-wrap/overflow-wrap-anywhere-001.html
	overflow-wrap/overflow-wrap-anywhere-003.html
        overflow-wrap/overflow-wrap-anywhere-fit-content-001.html
        overflow-wrap/overflow-wrap-cluster-002.html
        overflow-wrap/overflow-wrap-shaping-002.html
      </wpt>

    <dt><dfn>break-word</dfn></dt>
    <dd>As for ''overflow-wrap/anywhere'' except that
      <a>soft wrap opportunities</a> introduced by ''overflow-wrap/break-word''
      are <em>not</em> considered
      when calculating <a lt="min-content size">min-content intrinsic sizes</a>.

      <wpt>
        overflow-wrap/overflow-wrap-001.html
	overflow-wrap/overflow-wrap-break-word-001.html
	overflow-wrap/overflow-wrap-break-word-003.html
        overflow-wrap/overflow-wrap-break-word-008.html
        overflow-wrap/overflow-wrap-min-content-size-004.html
        overflow-wrap/overflow-wrap-break-word-fit-content-001.html
        overflow-wrap/overflow-wrap-cluster-001.html
        overflow-wrap/overflow-wrap-shaping-001.html
      </wpt>
    </dl>

    <p>For legacy reasons, UAs must treat 'word-wrap' as an [=legacy name alias=]
      of the 'overflow-wrap' property.

      <wpt>
        overflow-wrap/word-wrap-alias.html
        overflow-wrap/word-wrap-001.html
        overflow-wrap/word-wrap-002.html
        overflow-wrap/word-wrap-004.html
      </wpt>

<h3 id="word-break-shaping">
Shaping Across Intra-word Breaks</h3>

  <p>When shaping scripts such as Arabic <a>wrap</a>
  at unforced <a>soft wrap opportunities</a> within words
  (such as when breaking due to
  ''word-break: break-all'',
  ''line-break: anywhere'',
  ''overflow-wrap: break-word'',
  ''overflow-wrap: anywhere'',
  or when <a>hyphenating</a>)
  the characters must still be shaped
  (their joining forms chosen)
  as if the word were still whole.

  <wpt>
    hyphens/hyphens-shaping-001.html
    hyphens/hyphens-shaping-002.html
    line-break/line-break-shaping-001.html
    overflow-wrap/overflow-wrap-shaping-001.html
    overflow-wrap/overflow-wrap-shaping-002.html
    word-break/word-break-break-all-004.html
  </wpt>

  <div class="example">
    For example, if the word “نوشتن” is broken between the “ش” and “ت”,
    the “ش” still takes its initial form (“ﺷ”), and the “ت” its medial form (“ﺘ”)--
    forming as in “ﻧﻮﺷ | ﺘﻦ”, not as in “نوش | تن”.
  </div>

<h2 id="justification">
  Alignment and Justification</h2>

  <p>Alignment and justification controls how inline content is distributed within a line box.

  <h3 id="text-align-property" oldids="text-align">
    Text Alignment: the 'text-align' shorthand</h3>

    <pre class="propdef shorthand">
    Name: text-align
    Value: start | end | left | right | center | justify | match-parent | justify-all
    Initial: start
    Applies to: block containers
    Inherited: yes
    Canonical order: n/a
    Animation type: discrete
    </pre> 

    <wpt>
      inheritance.html
      parsing/text-align-valid.html
      parsing/text-align-invalid.html
    </wpt>

    <p>This <a>shorthand property</a>
      sets the 'text-align-all' and 'text-align-last' properties
      and describes how the inline-level content of a block
      is aligned along the inline axis
      if the content does not completely fill the line box.
      Values other than ''justify-all'' or ''match-parent'' are assigned to 'text-align-all'
      and reset 'text-align-last' to ''text-align-last/auto''.

    Values have the following meanings:

    <dl dfn-for=text-align dfn-type=value>
    <dt><dfn>start</dfn></dt>
      <dd>Inline-level content is aligned to the <a spec=css-writing-modes-3>start</a> edge of the line box.

         <wpt>
           text-align/text-align-006.html
           text-align/text-align-start-001.html
           text-align/text-align-start-002.html
           text-align/text-align-start-003.html
           text-align/text-align-start-004.html
           text-align/text-align-start-005.html
           text-align/text-align-start-006.html
           text-align/text-align-start-007.html
           text-align/text-align-start-008.html
           text-align/text-align-start-009.html
           text-align/text-align-start-010.html
           text-align/text-align-start-014.html
           text-align/text-align-start-015.html
           text-align/text-align-start-016.html
           text-align/text-align-start-017.html
           <!-- manual tests
           text-align/text-align-start-018.html
           text-align/text-align-start-019.html
           text-align/text-align-start-020.html
           text-align/text-align-start-021.html
           -->
         </wpt>
    <dt><dfn>end</dfn></dt>
      <dd>Inline-level content is aligned to the <a spec=css-writing-modes-3>end</a> edge of the line box.

         <wpt>
           text-align/text-align-007.html
           text-align/text-align-end-001.html
           text-align/text-align-end-002.html
           text-align/text-align-end-003.html
           text-align/text-align-end-004.html
           text-align/text-align-end-005.html
           text-align/text-align-end-006.html
           text-align/text-align-end-007.html
           text-align/text-align-end-008.html
           text-align/text-align-end-009.html
           text-align/text-align-end-010.html
           text-align/text-align-end-014.html
           text-align/text-align-end-015.html
           text-align/text-align-end-016.html
           text-align/text-align-end-017.html
           <!-- manual tests
           text-align/text-align-end-018.html
           text-align/text-align-end-019.html
           text-align/text-align-end-020.html
           text-align/text-align-end-021.html
           -->
         </wpt>
    <dt><dfn>left</dfn></dt>
      <dd>Inline-level content is aligned to the
        <a href="https://www.w3.org/TR/css-writing-modes-3/#line-left">line left</a>
        edge of the line box.
        (In vertical writing modes,
         this will be either the physical top or bottom,
         depending on 'text-orientation'.) [[CSS-WRITING-MODES-3]]
    <dt><dfn>right</dfn></dt>
      <dd>Inline-level content is aligned to the
        <a href="https://www.w3.org/TR/css-writing-modes-3/#line-right">line right</a>
        edge of the line box.
        (In vertical writing modes,
         this will be either the physical top or bottom,
         depending on 'text-orientation'.) [[CSS-WRITING-MODES-3]]
    <dt><dfn>center</dfn></dt>
      <dd>Inline-level content is centered within the line box.
    <dt><dfn>justify</dfn></dt>
      <dd>Text is justified according to the method specified by the 'text-justify' property,
        in order to exactly fill the line box.
        Unless otherwise specified by 'text-align-last',
        the last line before a forced break or the end of the block is ''start''-aligned.

        <wpt>
          text-align/text-align-justify-001.html
          text-align/text-align-justify-002.html
          text-align/text-align-justify-003.html
          text-align/text-align-justify-004.html
          text-align/text-align-justify-005.html
          text-align/text-align-justify-006.html
        </wpt>
    <dt><dfn>justify-all</dfn></dt>
      <dd>Sets both 'text-align-all' and 'text-align-last' to ''text-align/justify'',
        forcing the last line to justify as well.

        <wpt>
          text-align/text-align-justifyall-001.html
          text-align/text-align-justifyall-002.html
          text-align/text-align-justifyall-003.html
          text-align/text-align-justifyall-004.html
          text-align/text-align-justifyall-005.html
          text-align/text-align-justifyall-006.html
        </wpt>
    <dt><dfn>match-parent</dfn></dt>
      <dd>This value behaves the same as ''inherit''
        (computes to its parent's computed value)
        except that an <a>inherited value</a> of ''start'' or ''end''
        is interpreted against the parent’s
        (or the <a>initial containing block</a>’s, if there is no parent)
        'direction' value
        and results in a computed value of either 'left' or 'right'.
        When specified on the 'text-align' shorthand,
        sets both 'text-align-all' and 'text-align-last' to ''text-align/match-parent''.

        <wpt>
          text-align/text-align-008.html
        </wpt>
        <wpt pathprefix="/css/vendor-imports/mozilla/mozilla-central-reftests/text3/">
          text-align-match-parent-01.html
          text-align-match-parent-02.html
          text-align-match-parent-03.html
          text-align-match-parent-04.html
          text-align-match-parent-root-ltr.html
          text-align-match-parent-root-rtl.html
        </wpt>
    </dl>

    <p>A block of text is a stack of
      <a href="https://www.w3.org/TR/CSS2/visuren.html#line-box">line boxes</a>.
      This property specifies how the inline-level boxes within each line box
      align with respect to the start and end sides of the line box.
      Alignment is not with respect to the
      <a href="https://www.w3.org/TR/CSS2/visuren.html#viewport">viewport</a>
      or containing block.

    <p>In the case of ''justify'', the UA may stretch or shrink any inline boxes
      by <a href="#text-justify-property">adjusting</a> their text. (See 'text-justify'.)
      If an element's white space is not <a href="#collapse">collapsible</a>,
      then the UA is not required to adjust its text for the purpose of justification
      and may instead treat the text as having no <a>justification opportunities</a>.
      If the UA chooses to adjust the text, then it must ensure
      that <a>tab stops</a> continue to line up as required by the
      <a href="#white-space-rules">white space processing rules</a>.

      <wpt pathprefix="/css/CSS2/text">
        text-align-white-space-001.xht
        text-align-white-space-003.xht
        text-align-white-space-005.xht
        text-align-white-space-007.xht
      </wpt>

    <p>If (after justification, if any) the inline contents of a line box are too long to fit within it,
      then the contents are <a spec=css-writing-modes-3>start</a>-aligned:
      any content that doesn't fit overflows the line box's <a spec=css-writing-modes-3>end</a> edge.

    <p>See <a href="#bidi-linebox">Bidirectionality and line boxes</a>
      for details on how to determine the <a spec=css-writing-modes-3>start</a> and <a spec=css-writing-modes-3>end</a> edges of a line box.

  <h3 id="text-align-all-property" oldids="text-align-all">
    Default Text Alignment: the 'text-align-all' property</h3>

    <pre class="propdef">
    Name: text-align-all
    Value: start | end | left | right | center | justify | match-parent
    Initial: start
    Applies to: block containers
    Inherited: yes
    Computed value: keyword as specified, except for ''match-parent'' which computes as defined above
    Canonical order: n/a
    Animation type: discrete
    </pre>

    <wpt>
      inheritance.html
      parsing/text-align-all-valid.html
      parsing/text-align-all-invalid.html
    </wpt>

    <p>This longhand of the 'text-align' <a>shorthand property</a>
    specifies the inline alignment of all lines of inline content in the block container,
    except for last lines overridden by a non-''text-align-last/auto'' value of 'text-align-last'.
    See 'text-align' for a full description of values.

    <p class="advisement">
    Authors should use the 'text-align' shorthand instead of this property.

  <h3 id="text-align-last-property" caniuse="css-text-align-last" oldids="text-align-last">
    Last Line Alignment: the 'text-align-last' property</h3>

    <pre class="propdef">
    Name: text-align-last
    Value: auto | start | end | left | right | center | justify | match-parent
    Initial: auto
    Applies to: block containers
    Inherited: yes
    Canonical order: n/a
    Computed value: specified keyword
    Animation type: discrete
    </pre>

    <wpt>
      inheritance.html
      parsing/text-align-last-valid.html
      parsing/text-align-last-invalid.html
      <!-- manual test
      text-align/text-align-last-013.html
      text-align/text-align-last-014.html
      -->
    </wpt>

    <p>This property describes how the last line of a block or a line
      right before a <a>forced line break</a> is aligned.

      <wpt>
        <!-- manual test
        text-align/text-align-last-001.html
        text-align/text-align-last-002.html
        text-align/text-align-last-003.html
        text-align/text-align-last-004.html
        text-align/text-align-last-005.html
        text-align/text-align-last-006.html
        -->
        text-align/text-align-last-010.html
        text-align/text-align-last-011.html
        <!-- manual test
        text-align/text-align-last-012.html
        -->
      </wpt>

    <p>If <dfn dfn-for=text-align-last dfn-type=value>auto</dfn> is specified,
      content on the affected line is aligned per 'text-align-all'
      unless 'text-align-all' is set to ''justify'',
      in which case it is start-aligned.
      All other values are interpreted as described for 'text-align'.

      <wpt>
        <!-- manual test
        text-align/text-align-last-007.html
        text-align/text-align-last-008.html
        text-align/text-align-last-009.html
        -->
      </wpt>

  <h3 id="text-justify-property" caniuse="css-text-justify" oldids="text-justify">
    Justification Method: the 'text-justify' property</h3>

    <pre class="propdef">
    Name: text-justify
    Value: auto | none | inter-word | inter-character
    Initial: auto
    Applies to: <a>inline boxes</a>
    Inherited: yes
    Canonical order: n/a
    Computed value: specified keyword
    Animation type: discrete
    </pre>

    <wpt>
      inheritance.html
      parsing/text-justify-valid.html
      parsing/text-justify-invalid.html
    </wpt>

    <p>This property selects the justification method used when a line's
      alignment is set to ''justify'' (see 'text-align').
      The property applies to inlines,
      but is inherited from block containers to the root inline box containing their inline-level contents.
      It takes the following values:</p>

    <dl dfn-for=text-justify dfn-type=value>
      <dt><dfn>auto</dfn></dt>
        <dd>The UA determines the justification algorithm to follow, based
          on a balance between performance and adequate presentation quality.
          Since justification rules vary by writing system and language,
          UAs should, where possible, use a justification algorithm appropriate to the text.

          <p class="example">
          For example, the UA could use by default a justification method that is a
          simple universal compromise for all writing systems&mdash;such as
          primarily expanding <a>word separators</a>
          and between CJK <a>typographic letter units</a>
          along with secondarily expanding between Southeast Asian <a>typographic letter units</a>.
          Then, in cases where the <a>content language</a> of the paragraph is known,
          it could choose a more language-tailored justification behavior
          e.g. following [[JLREQ]] for Japanese,
          using cursive elongation for Arabic,
          using ''inter-word'' for German,
          etc.

        <div class="figure" id="fig-text-justify-cursive">
          <p>
            <img alt="Two lines of calligraphic Arabic end together due to a mix of compressed and swash forms."
                 title="Swash forms elongate the first line while a compressed contextual ligature shortens the second, allowing both to end precisely together."
                 src="images/text-justify-cursive.png"></p>
          <p class="caption">An example of cursively-justified Arabic text,
          rendered by <a href="http://www.decotype.com/">Tasmeem</a>.
          Like English, Arabic can be justified by adjusting the spacing between words,
          but in most styles it can also be justified by calligraphically elongating or compressing the letterforms themselves.
          In this example, the upper text is extended to fill the line by the use of elongated (kashida) forms and swash forms,
          while the bottom line is compressed slightly by using a stacked combination for the characters between ت and م.
          By employing traditional calligraphic techniques,
          a typesetter can justify the line while preserving flow and color,
          providing a very high quality justification effect.
          However, this is by its nature a very script-specific effect.
        </div>

        <div class="figure" id="fig-text-justify-compromise">
          <p>
            <img alt="Extra space is partly to spaces and partly among CJK and Thai letters."
                 src="images/text-justify-compromise.png"></p>
          <p class="caption">Mixed-script text with ''text-justify: auto'':
            this interpretation uses a universal-compromise justification method,
            expanding at spaces as well as between CJK and Southeast Asian letters.
            This effectively uses inter-word + inter-ideograph spacing
            for lines that have word-separators and/or CJK characters
            and falls back to inter-cluster behavior for lines that don't
            or for which the space stretches too far.
        </div>

      <dt><dfn>none</dfn></dt>
        <dd>Justification is disabled: there are no <a>justification opportunities</a> within the text.

          <wpt>
            text-justify/text-justify-001.html
          </wpt>
          <wpt pathprefix="/css/vendor-imports/mozilla/mozilla-central-reftests/text3/">
            text-justify-none-001.html
          </wpt>
          <div class="figure" id="fig-text-justify-none">
            <p>
              <img alt="No extra space is insesrted."
                   src="images/text-justify-none.png"></p>
            <p class="caption">Mixed-script text with ''text-justify: none''
          </div>
          <p class="note">Note: This value is intended for use in user stylesheets
          to improve readability or for accessibility purposes.

      <dt><dfn>inter-word</dfn></dt>
        <dd>Justification adjusts spacing at <a>word separators</a> only
          (effectively varying the used 'word-spacing' on the line).
          This behavior is typical for languages that separate words using spaces,
          like English or Korean.

          <wpt pathprefix="/css/vendor-imports/mozilla/mozilla-central-reftests/text3/">
            text-justify-inter-word-001.html
          </wpt>
          <div class="figure" id="fig-text-justify-interword">
            <p>
              <img alt="Extra space is equally distributed mainly to spaces."
                   src="images/text-justify-interword.png"></p>
            <p class="caption">Mixed-script text with ''text-justify: inter-word''
          </div>
      <dt><dfn>inter-character</dfn></dt>
        <dd>Justification adjusts spacing between each pair of adjacent <a>typographic character units</a>
          (effectively varying the used 'letter-spacing' on the line).
          This value is sometimes used in East Asian systems such as Japanese.

          <wpt>
          <!-- manual test
            text-justify/text-justify-002.html
          -->
          </wpt>
          <wpt pathprefix="/css/vendor-imports/mozilla/mozilla-central-reftests/text3/">
            text-justify-inter-character-001.html
          </wpt>
          <div class="figure" id="fig-text-justify-distribute">
            <p>
              <img alt="Extra space is equally distributed at points between spaces and letters of all writing systems."
                   src="images/text-justify-distribute.png"></p>
            <p class="caption">Mixed-script text with ''text-justify: inter-character''
          </div>
          For legacy reasons, UAs must also support the alternate keyword <dfn>distribute</dfn>
          with the exact same meaning and behavior.

          <wpt>
          <!-- manual test
            text-justify/text-justify-003.html
          -->
          </wpt>
          <wpt pathprefix="/css/vendor-imports/mozilla/mozilla-central-reftests/text3/">
            text-justify-distribute-001.html
          </wpt>
    </dl>

    <p class="advisement">
      Since optimal justification is language-sensitive,
      authors should correctly language-tag their content for the best results.

  Note: The guidelines in this level of CSS do not describe a complete
    justification algorithm. They are merely a minimum set of requirements
    that a complete algorithm should meet. Limiting the set of requirements
    gives UAs some latitude in choosing a justification algorithm that
    meets their needs and desired balance of quality, speed, and complexity.

<h4 id="expanding-text">
Expanding and Compressing Text</h4>

  <p>When justifying text, the user agent takes the remaining space between
    the ends of a line's contents and the edges of its line box, and
    distributes that space throughout its contents so that the contents
    exactly fill the line box.
    The user agent may alternatively distribute negative space,
    putting more content on the line than would otherwise fit under normal spacing conditions.

  <p>A <span id="expansion-opportunity"><dfn export>justification opportunity</dfn></span> is
    a point where the justification algorithm may alter spacing within the text.
    A justification opportunity can be provided by a single <a>typographic character unit</a>
    (such as a <a>word separator</a>),
    or by the juxtaposition of two <a>typographic character units</a>.
    As with controls for <a href="#line-break-details">soft wrap opportunities</a>,
    whether a <a>typographic character unit</a> provides a <a>justification opportunity</a>
    is controlled by the 'text-justify' value of its parent;
    similarly, whether a <a>justification opportunity</a> exists between two consecutive <a>typographic character units</a>
    is determined by the 'text-justify' value of their nearest common ancestor.

  <p>
    Space distributed by justification is <em>in addition to</em>
    the spacing defined by the 'letter-spacing' or 'word-spacing' properties.
    When such additional space is distributed to a <a>word separator</a> <a>justification opportunity</a>,
    it is applied under the same rules as for 'word-spacing'.
    Similarly, when space is distributed to an <a>justification opportunity</a> between
    two <a>typographic character units</a>,
    it is applied under the same rules as for 'letter-spacing'.


  <p>A justification algorithm may divide <a>justification opportunities</a> into different priority levels.
    All <a>justification opportunities</a> within a given level
    are expanded or compressed at the same priority,
    regardless of which <a>typographic character units</a> created that opportunity.
    For example, if <a>justification opportunities</a> between two Han characters
    and between two Latin letters are defined to be at the same level
    (as they are in the ''inter-character'' justification style),
    they are not treated differently because they originate from different <a>typographic character units</a>.
    It is not defined in this level
    whether or how other factors
    (such as font size, letter-spacing, glyph shape, position within the line, etc.)
    may influence the distribution of space to <a>justification opportunities</a> within the line.

  <p>The UA may enable or break optional ligatures or use other font features
  such as alternate glyphs or glyph compression
  to help justify the text under any method.
  This behavior is not controlled by this level of CSS.
  However, UAs <em>must not</em> break required ligatures
  or otherwise disable features required to correctly shape complex scripts.

  <p>If a <a>justification opportunity</a> exists within a line,
     and <a href="#text-align-property">text alignment</a> specifies
     full justification (''text-align/justify'') for that line,
     it must be justified.

<h4 id="justify-symbols">
Handling Symbols and Punctuation</h4>

    <p>When determining <a>justification opportunities</a>,
      a <a>typographic character unit</a> from the Unicode Symbols (S*) and Punctuation (P*) classes
      is generally treated the same as a <a>typographic letter unit</a> of the same script
      (or, if the character's script property is Common,
      then as a <a>typographic letter unit</a> of the dominant script).

    <p>However, by typographic tradition there may be additional rules
      controlling the justification of symbols and punctuation.
      Therefore, the UA may reassign specific characters
      or introduce additional levels of prioritization
      to handle <a>justification opportunities</a> involving symbols and punctuation.

    <p class="example">
      For example, there are traditionally no <a>justification opportunities</a>
      between consecutive
      U+2014 Em Dash ‘—’,
      U+2015 Horizontal Bar ‘―’,
      U+2026 Horizontal Ellipsis ‘…’,
      or U+2025 Two Dot Leader ‘‥’
      characters [[JLREQ]];
      thus a UA might assign these characters to a “never” prioritization level.
      As another example, certain fullwidth punctuation characters
      (such as U+301A Left White Square Bracket ‘〚’)
      are considered to contain a <a>justification opportunity</a> in Japanese.
      The UA might therefore assign these characters to a higher prioritization
      level than the opportunities between ideographic characters.

<h4 id="justify-limits">
Unexpandable Text</h4>

    <p>If the inline contents of a line cannot be stretched to the full width of the line box,
      then they must be aligned as specified by the 'text-align-last' property.
      (If 'text-align-last' is ''justify'', then
       they must be aligned as for ''center''.)

<h4 id="justify-cursive">
Cursive Scripts</h4>

    <p>Justification <em>must not</em> introduce gaps between the joined <a>typographic letter units</a>
      of <a>cursive scripts</a> such as Arabic.
      If it is able, the UA <em>may</em>
      translate space distributed to <a>justification opportunities</a> within a run of such <a>typographic letter units</a>
      into some form of cursive elongation for that run.
      It otherwise <em>must</em> assume that no <a>justification opportunity</a> exists
      between any pair of <a>typographic letter units</a> in <a>cursive script</a>
      (regardless of whether they join).

      <wpt>
      <!-- manual tests
        text-justify/text-justify-004.html
        text-justify/text-justify-005.html
      -->
      </wpt>

    <div class="example">
      <p>The following are examples of unacceptable justification:
      <div class="figure">
        <p><img alt="" src="images/arabic-stretch-spaced.png">
        <p class="caption">Adding gaps between every pair of Arabic letters
      </div>
      <div class="figure">
        <p><img alt="" src="images/arabic-stretch-unjoined.png">
        <p class="caption">Adding gaps between every pair of unjoined Arabic letters
      </div>
    </div>

    <p>Some font designs allow for the use of the tatweel character for justification.
    A UA that performs tatweel-based justification must properly handle the rules for its use.
    Note that correct insertion of tatweel characters depends on context, including
    the letter-combinations involved, location within the word, and location of the word within the line.

<h4 id="justify-algos">
Minimum Requirements for ''text-justify/auto'' Justification</h4>

  <p>For <a value for=text-justify>auto</a> justification, this specification does not define
  what all of the <a>justification opportunities</a> are,
  how they are prioritized, or
  when and how multiple levels of <a>justification opportunities</a> interact.
  However, it does require that

  <ul>
    <li>
      Unless contraindicated by the typographic traditions of the <a>content language</a> or adjacent symbols/punctuation,
      each of the following provides a <a>justification opportunity</a>:
      <ul>
        <li><a>Word separators</a>
        <li>The boundary between a <a>typographic character unit</a> of any <a>block scripts</a> and any other <a>typographic character unit</a>
        <li>The boundary between a <a>typographic character unit</a> of any <a>clustered scripts</a> and any other <a>typographic character unit</a>
      </ul>
    <li>
      All <a>letters</a> belonging to all <a>block scripts</a> are treated the same,
      and all <a>letters</a> belonging to all <a>clustered scripts</a> are treated the same.
      For example, no distiction is made between
      the justification opportunity between a Han letter followed by another Han letter,
      vs. the justification opportunity between a Han letter followed by a Hangul letter.
  </ul>

  Further information on text justification can be found in (or submitted to) <a href="https://www.w3.org/International/articles/typography/justification">“Approaches to Full Justification”</a>,
  which indexes by writing system and language,
  and is maintained by the <a href="https://www.w3.org/International/">W3C Internationalization Working Group</a>. [[JUSTIFY]]

<h2 id="spacing">
  Spacing</h2>

  <p>CSS offers control over text spacing
  via the 'word-spacing' and 'letter-spacing' properties, which specify additional space
  around <a>word separators</a> or between <a>typographic character units</a>, respectively.

<h3 id="word-spacing-property" oldids="word-spacing">
Word Spacing: the 'word-spacing' property</h3>

  <pre class="propdef">
  Name: word-spacing
  Value: normal | <<length>>
  Initial: normal
  Applies to: <a>inline boxes</a>
  Inherited: yes
  Percentages: N/A
  Computed value: an absolute length
  Animation type: by computed value type
  Canonical order: n/a
  </pre>

  <wpt>
    inheritance.html
    parsing/word-spacing-valid.html
    parsing/word-spacing-invalid.html
  </wpt>

    <p>This property specifies additional spacing
      between &ldquo;words&rdquo;.
      Missing values are assumed to be ''word-spacing:normal''.
      Values are interpreted as defined below:

  <dl dfn-for=word-spacing dfn-type=value>
    <dt><dfn>normal</dfn>
      <dd>No additional spacing is applied.
        Computes to zero.
    <dt><dfn>&lt;length&gt;</dfn>
      <dd>Specifies extra spacing <em>in addition to</em>
        the intrinsic inter-word spacing defined by the font.
        <wpt>
          tab-size/tab-size-spacing-001.html
        </wpt>
  </dl>

  <p>Additional spacing is applied to each <a>word separator</a>
    left in the text after the <a href="#white-space-rules">white space processing rules</a> have been applied,
    and should be applied half on each side of the character
    unless otherwise dictated by typographic tradition.
    Values may be negative, but there may be implementation-dependent limits.

    <p><dfn id="word-separator" lt="word-separator character | word separator">Word-separator characters</dfn>
      are <a>typographic character units</a> whose purpose and general usage is to separate words.
      In [[UNICODE]] this includes
      the space (U+0020), the no-break space (U+00A0), the Ethiopic word space (U+1361),
      the Aegean word separators (U+10100,U+10101), the Ugaritic word divider (U+1039F),
      and the Phoenician Word Separator (U+1091F).

      If there are no word-separator characters, or if a word-separating
      character has a zero advance width (such as the zero width space U+200B)
      then the user agent must not create an additional spacing between words.

      General punctuation (from U+2000 to U+206F)
      and fixed-width spaces (such as U+3000 and U+2000 through U+200A)
      are not considered word-separator characters.</p>

  <h3 id="letter-spacing-property" caniuse="css-letter-spacing" oldids="letter-spacing">
    Tracking: the 'letter-spacing' property</h3>

    <pre class="propdef">
    Name: letter-spacing
    Value: normal | <<length>>
    Initial: normal
    Applies to: <a>inline boxes</a>
    Inherited: yes
    Computed value: an absolute length
    Animation type: by computed value type
    Canonical order: n/a
    </pre>

    <wpt>
      inheritance.html
      parsing/letter-spacing-valid.html
      parsing/letter-spacing-invalid.html
    </wpt>

  <p>This property specifies additional spacing (commonly called <dfn export>tracking</dfn>)
  between adjacent <a>typographic character units</a>.
  Letter-spacing is applied after
  <a href="https://www.w3.org/TR/css-writing-modes/#text-direction">bidi reordering</a> [[CSS-WRITING-MODES-3]]
  and is in addition to
  <a href="https://www.w3.org/TR/css-fonts/#font-kerning-prop">kerning</a> [[CSS-FONTS-3]]
  and 'word-spacing'.
  Depending on the justification rules in effect,
  user agents may further increase or decrease the space between <a>typographic character units</a>
  in order to <a href="#text-justify-property">justify text</a>.

  <wpt>
    letter-spacing/letter-spacing-bidi-001.html
  </wpt>
  <wpt pathprefix="/css/CSS2">
    bidi-005.xht
    bidi-006.xht
    bidi-007.xht
    bidi-008.xht
    bidi-009.xht
    bidi-010.xht
    bidi-text/bidi-005b.xht
    bidi-text/bidi-006b.xht
    bidi-text/bidi-007b.xht
    bidi-text/bidi-008b.xht
    bidi-text/bidi-009b.xht
    bidi-text/bidi-010b.xht
  </wpt>

  <p>Values have the following meanings:

  <dl dfn-for=letter-spacing dfn-type=value>
    <dt><dfn>normal</dfn>
      <dd>No additional spacing is applied. Computes to zero.
    <dt><dfn>&lt;length&gt;</dfn>
      <dd>Specifies <em>additional</em> spacing between <a>typographic character units</a>.
        Values may be negative, but there may be implementation-dependent limits.
        <wpt>
          tab-size/tab-size-spacing-001.html
        </wpt>
  </dl>

  <p>For <a href="https://github.com/w3c/csswg-drafts/issues/1484">legacy reasons</a>,
  a computed 'letter-spacing' of zero
  yields a <a>resolved value</a> (<code>getComputedStyle()</code> return value)
  of ''letter-spacing/normal''.

    <p>For the purpose of 'letter-spacing', each consecutive run of atomic
      inlines (such as images and inline blocks) is treated as a single
      <a>typographic character unit</a>.

    <p>Letter-spacing must not be applied at the beginning or at the end of a line.

    <wpt>
      letter-spacing/letter-spacing-end-of-line-001.html
      tab-size/tab-size-spacing-001.html
    </wpt>

  <div class="example">
    <p>Because letter-spacing is not applied at the beginning or end of a line,
    text always fits flush with the edge of the block.
    <pre>
      p    { letter-spacing: 1em; }

      &lt;p>abc&lt;/p></pre>

    <p class="ls-ex good ls-fixed-width color-box" style="text-align: left">a&#x3000;b&#x3000;c</p>
    <p class="ls-ex good ls-fixed-width color-box" style="text-align: right">a&#x3000;b&#x3000;c</p>

    <p>UAs therefore must not append letter spacing to the right or trailing edge of a line:</p>

    <p class="ls-ex bad ls-fixed-width color-box" style="text-align: right">a&#x3000;b&#x3000;c&#x3000;</p>
  </div>

    <p>Letter spacing between two <a>typographic character units</a> effectively “belongs”
      to the innermost element that contains the two <a>typographic character units</a>:
      the total letter spacing between two adjacent <a>typographic character units</a> (after bidi reordering)
      is specified by and rendered within
      the innermost element that <em>contains</em> the boundary between the two <a>typographic character units</a>.

      <wpt>
        letter-spacing/letter-spacing-bidi-002.html
        letter-spacing/letter-spacing-nesting-001.html
        letter-spacing/letter-spacing-nesting-002.html
      </wpt>

  <div class="example">
    <p>A given value of 'letter-spacing' only affects the spacing
    between characters completely contained within the element for which it is specified:

    <pre>
      p    { letter-spacing: 1em; }
      span { letter-spacing: 2em; }

      &lt;p>a&lt;span>bb&lt;/span>c&lt;/p></pre>

    <p class="ls-ex">a&#x3000;<span class="color-box">b&#x3000;&#x3000;b</span>&#x3000;c</p>

    <p>This also means that applying 'letter-spacing' to
    an element containing only a single character
    has no effect on the rendered result:

    <pre>
      p    { letter-spacing: 1em; }
      span { letter-spacing: 2em; }

      &lt;p>a&lt;span>b&lt;/span>c&lt;/p></pre>

    <p class="ls-ex">a&#x3000;<span class="color-box">b</span>&#X3000;c</p>

    <p>An inline box only includes
    letter spacing between characters completely contained within that element:

    <pre>
      p    { letter-spacing: 1em; }

      &lt;p>a&lt;span>bb&lt;/span>c&lt;/p></pre>

    <p class="ls-ex good">a&#x3000;<span class="color-box">b&#x3000;b</span>&#x3000;c</p>

    <p>It is incorrect to include the letter spacing on the right or trailing edge of the element:

    <p class="ls-ex bad">a&#x3000;<span class="color-box">b&#x3000;b&#x3000;</span>c</p>

    <p>Letter spacing is inserted <strong>after</strong> RTL reordering,
    so the letter spacing applied to the inner span below has no effect,
    since after reordering the "c" doesn't end up next to "&#x5d0;":
    <pre>
      p    { letter-spacing: 1em; }
      span { letter-spacing: 2em; }

      &lt;!-- abc followed by Hebrew letters alef (&#x5d0;), bet (&#x5d1;) and gimel (&#x5d2;) -->
      &lt;!-- Reordering will display these in reverse order. --&gt;
      <bdo dir=ltr>&lt;p>ab&lt;span>c&#x5d0;&lt;/span>&#x5d1;&#x5d2;&lt;/p></bdo></pre>

    <p class="ls-ex">a&#x3000;b</span>&#x3000;<span class="color-box">c</span>&#x3000;<span class="color-box">&#x5d0;</span>&#x3000;&#x5d1;&#x3000;&#x5d2;</p>
  </div>

    <p>Letter spacing ignores invisible zero-width formatting characters
      (such as those from the Unicode Cf category).
      Spacing must be added as if those characters did not exist in the document.

      <wpt>
        letter-spacing/letter-spacing-control-chars-001.html
      </wpt>

    <p class="example">For example, 'letter-spacing' applied to
      <code>A&amp;#x200B;B</code> is identical to <code>AB</code>,
      regardless of where any element boundaries might fall.

    <p>When the effective spacing between two characters is not zero
      (due to either <a href="#text-justify-property">justification</a>
      or a non-zero value of 'letter-spacing'),
      user agents should not apply optional ligatures,
      i.e. those that are not defined as required
      for fundamentally correct glyph shaping.
      However, ligatures and other font features
      specified via the low-level 'font-feature-settings' property
      take precedence over this rule.
      See [[css-fonts-3#feature-precedence]].

    <div class="example">
      For example, if the word “filial” is letter-spaced,
      an “fi” ligature should not be used
      as it will prevent even spacing of the text.

      <figure>
        <p><strong style="letter-spacing: 0.5em">filial</strong> vs <strong style="letter-spacing: 0.5em">filial</strong>
      </figure>
    </div>

    Note: In OpenType, required ligatures are expected
    to be associated to the <code>rlig</code> feature.
    All other ligatures are therefore considered optional.
    In some cases, however, UA or platform heuristics
    apply additional ligatures in order to handle broken fonts;
    this specification does not define or override such exceptional handling.

<h4 id="cursive-tracking">
Cursive Scripts</h4>

    <p>If it is able, the UA <em>may</em> apply letter spacing to <a>cursive scripts</a>
    by translating the total extra space to be distributed to a run of such letters
    into some form of cursive elongation (or compression, for negative tracking values) for that run
    that results in an equivalent total expansion (or compression) of the run.
    Otherwise, if the UA cannot expand text from a <a>cursive script</a>
    without breaking its cursive connections,
    it <em>must not</em> apply spacing
    between any pair of that script's <a>typographic letter units</a> at all
    (effectively treating each word as a single <a>typographic letter unit</a>
    for the purpose of letter-spacing).
    Both cases will result in an effective spacing of zero between such letters;
    however the former will preserve the sense of stretching out the text.

    <div class="example">
      <p>Below are some appropriate and inappropriate examples of spacing out Arabic text.
      <table class="data">
      <thead>
        <tr><td><img src="images/arabic-stretch-original.png" alt="">
            <td>&mdash;
            <td>Original text
      <tbody>
        <tr><td><img src="images/arabic-stretch-spaced.png" alt="">
            <td class="no">BAD
            <th>Even distribution of space between each letter.
                <em>Notice this breaks cursive joins!</em>
        <tr><td><img src="images/arabic-stretch-kashida.png" alt="">
            <td class="ok">OK
            <th>Distributing &sum;<var>letter-spacing</var> by typographically-appropriate cursive elongation.
            <em>The resulting text is as long as the previous evenly-spaced example.</em>
        <tr><td><img src="images/arabic-stretch-suppressed.png" alt="">
            <td class="ok">OK
            <th>Suppressing 'letter-spacing' between Arabic letters.
                <em>Notice 'letter-spacing' is nonetheless applied to non-Arabic characters (like spaces).</em>
        <tr><td><img src="images/arabic-stretch-unjoined.png" alt="">
            <td class="no">BAD
            <th>Applying 'letter-spacing' only between non-joined letters.
                <em>This distorts typographic color and obfuscates word boundaries.</em>
      </table>
    </div>
    <div class="note">
      Note: Proper cursive elongation or compression of a text
      can vary depending on the
      script, typeface, language,
      location within a word, location within a line,
      implementation complexity, font capabilities,
      and calligraphic preferences,
      and may not be possible in certain cases at all.
      It may involve the use of shortening ligatures,
      swash variants, contextual forms,
      elongation glyphs such as U+0640 ARABIC TATWEEL,
      or other microtypography.
      It is outside the scope of CSS to define rules for these effects.
      Authors should avoid applying 'letter-spacing' to cursive scripts
      unless they are prepared to accept non-interoperable results.
    </div>

  <h3 id="boundary-shaping">
  Shaping Across Element Boundaries</h3>

  Text shaping <em>must</em> be broken at inline box boundaries
  when any of the following are true
  for any box whose boundary separates the two <a>typographic character units</a>:

  * Any of 'margin'/'border'/'padding'
    separating the two <a>typographic character units</a> in the inline axis
    is non-zero.

    <wpt>
      shaping/shaping-009.html
      shaping/shaping-010.html
      shaping/shaping-011.html
      boundary-shaping/boundary-shaping-003.html
      boundary-shaping/boundary-shaping-004.html
      boundary-shaping/boundary-shaping-005.html
      boundary-shaping/boundary-shaping-007.html
      boundary-shaping/boundary-shaping-009.html
    </wpt>
  * 'vertical-align' is not ''vertical-align/baseline''.

    <wpt>
      boundary-shaping/boundary-shaping-002.html
      boundary-shaping/boundary-shaping-006.html
    </wpt>
  * The boundary is a <a lt="bidi-isolates">bidi isolation boundary</a>.

    <wpt>
      shaping/shaping-012.html
      shaping/shaping-013.html
      boundary-shaping/boundary-shaping-008.html
    </wpt>

  Text shaping <em>must not</em> be broken across inline box boundaries
  when there is no effective change in formatting,
  or if the only formatting changes do not affect the glyphs
  (as in applying <a href="https://www.w3.org/TR/css-text-decoration/">text decoration</a>).

  <wpt>
    text-transform/text-transform-shaping-001.html
    text-transform/text-transform-shaping-002.html
    text-transform/text-transform-shaping-003.html
    shaping/shaping-000.html
    shaping/shaping-004.html
    shaping/shaping-005.html
    shaping/shaping-006.html
    shaping/shaping-007.html
    shaping/shaping-014.html
    shaping/shaping-016.html
    shaping/shaping-022.html
    shaping/shaping-025.html
    shaping/shaping_lig-000.html
    boundary-shaping/boundary-shaping-001.html
    boundary-shaping/boundary-shaping-010.html
  </wpt>

  Text shaping <em>should not</em> be broken across inline box boundaries otherwise,
  if it is reasonable and possible for that case given the limitations of the font technology.

  <wpt>
    shaping/shaping-001.html
    shaping/shaping-002.html
    shaping/shaping-003.html
    shaping/shaping-008.html
    shaping/shaping-017.html
    shaping/shaping-018.html
    shaping/shaping-020.html
    shaping/shaping-021.html
    shaping/shaping-023.html
    shaping/shaping-024.html
    boundary-shaping/boundary-shaping-009.html
  </wpt>

  <div class="example">
    An example of reasonable and possible shaping across boundaries
    is Arabic shaping:
    in many systems this is performed by the font engine,
    allowing the font to provide variant glyphs
    with potentially very sophisticated contextual shaping.
    It's not generally possible to rely on this system across a font change
    unless the font engine has an API to provide context,
    but it is straightforward and therefore quite reasonable
    for an engine to work around this limitation by, for example,
    using the zero-width-joiner (U+200D) or zero-width-non-joiner (U+200C)
    as appropriate to solicit the correct choice of
    initial/medial/final/isolated glyph.

    An example of possible but not reasonable shaping across boundaries
    is handling a font that is sensitive to 20 characters of context
    on either side to choose its glyphs:
    passing all the text before <em>and after</em> the string in question,
    even through multiple inline boundaries with formatting changes,
    is complicated.
    The UA <em>could</em> handle such cases,
    but is not required to,
    as they are not typical or fundamentally required
    by any modern writing system.

    An example of impossible shaping accross boundaries
    is a change in font weight partway through the word “and”
    in a font where a ligature would replace
    all three letters of the word “and”
    with an ampersand glyph (“&amp;”).
<!--
    It's simply not possible for the UA
    to create the effect of a partway-bold single glyph.
-->
  </div>

<h2 id="edge-effects">
  Edge Effects</h2>

  <p>Edge effects control
    the indentation of lines with respect to other lines in the block ('text-indent')
    and how content is measured at the start and end edges of a line ('hanging-punctuation').

  <h3 id="text-indent-property" caniuse="css-text-indent" oldids="text-indent">
    First Line Indentation: the 'text-indent' property</h3>

    <pre class="propdef">
    Name: text-indent
    Value: [ <<length-percentage>> ] && hanging? && each-line?
    Initial: 0
    Applies to: block containers
    Inherited: yes
    Percentages: refers to block container’s own <a>inline-axis</a> <a>inner size</a>
    Computed value: computed <<length-percentage>> value, plus any specified keywords
    Animation type: by computed value type
    Canonical order: <abbr title="follows order of property value definition">per grammar</abbr>
    </pre>

    <wpt>
      inheritance.html
      parsing/text-indent-valid.html
      parsing/text-indent-invalid.html
    </wpt>

    <p>This property specifies the indentation applied to lines of inline
      content in a block. The indent is treated as a margin applied to
      the start edge of the line box.

    <p>Unless otherwise specified by the ''each-line'' and/or <a value for=text-indent>hanging</a> keywords,
      only lines that are the
      <a href="https://www.w3.org/TR/CSS2/selector.html#first-line-pseudo">first formatted line</a> [[!CSS2]]
      of an element are affected.
      For example, the first line of an anonymous block box is only affected
      if it is the first child of its parent element.

    <p>Values have the following meanings:</p>

    <dl dfn-for=text-indent dfn-type=value>
      <dt><dfn>&lt;length&gt;</dfn>
      <dd>Gives the amount of the indent as an absolute length.</dd>
      <dt><dfn>&lt;percentage&gt;</dfn>
      <dd>Gives the amount of the indent as a percentage of
        the block container’s own <a>logical width</a>

        Percentages must be treated as ''0'' for the purpose of calculating [=intrinsic size contributions=],
        but are always resolved normally when performing layout.

        <wpt>
          text-indent/percentage-value-intrinsic-size.html
          text-indent/text-indent-percentage-001.xht
          text-indent/text-indent-percentage-002.html
          text-indent/text-indent-percentage-003.html
          text-indent/text-indent-percentage-004.html
        </wpt>

        Note: This can lead to the element overflowing.
        It is not recommended to use percentage indents and intrinsic sizing toghether.
      </dd>
      <dt><dfn>each-line</dfn>
      <dd>Indentation affects the first line of each block container
        and each line after a <a>forced line break</a>
        (but not lines after a <a>soft wrap break</a>).
      <dt><dfn>hanging</dfn>
      <dd>Inverts which lines are affected.</dd>
    </dl>

    <div class="example">
      <p>If 'text-align' is ''start'' and 'text-indent' is ''5em'' in
      left-to-right text with no floats present, then first line of text
      will start 5em into the block:</p>

      <pre class="output">
             Since CSS1 it has been possible to
        indent the first line of a block element
        5em by setting the 'text-indent' property&nbsp;
        to '5em'.
      </pre>
      <p>If we add the ''text-indent/hanging'' keyword,
      then the first line will start flush,
      but other lines will be indented 5em:
      <pre class="output">
        In CSS3 we can instead indent all other
             lines of the block element by 5em
             by setting the 'text-indent' property
             to 'hanging 5em'.
      </pre>
    </div>

    <div class="example">
      <p>Since the 'text-indent' property only affects the “first formatted line”,
      a line after a forced break will not be indented.
      <pre class="output">
           For example, in the middle of
        this paragraph is an equation,
        which is centered:
                     x + y = z
        The first line after the equation
        is flush (else it would look like
        we started a new paragraph).
      </pre>
      <p>However, sometimes (as in poetry or code),
      it is appropriate to indent each line
      that happens to be long enough to wrap.
      In the following example, 'text-indent'
      is given a value of ''3em hanging each-line'',
      giving the third line of the poem a hanging indent
      where it soft-wraps at the block's right boundary:
      <pre class="output">
        In a short line of text
        There need be no wrapping,
        But when we go on and on and on&nbsp;&nbsp;
           and on,
        Sometimes a soft break
        Can help us stay on the page.
      </pre>
    </div>

    <p class="note">Note: Since the 'text-indent' property inherits,
      when specified on a block element, it will affect descendant
      inline-block elements.
      For this reason, it is often wise to specify 'text-indent: 0' on
      elements that are specified 'display: inline-block'.</p>

  <h3 id="hanging-punctuation-property" caniuse="css-hanging-punctuation" oldids="hanging-punctuation">
    Hanging Punctuation: the 'hanging-punctuation' property</h3>

    <pre class="propdef">
    Name: hanging-punctuation
    Value: none | [ first || [ force-end | allow-end ] || last ]
    Initial: none
    Applies to: <a>inline boxes</a>
    Inherited: yes
    Canonical order: <abbr title="follows order of property value definition">per grammar</abbr>
    Computed value: specified keyword(s)
    Animation type: discrete
    </pre>

    <wpt>
      inheritance.html
      parsing/hanging-punctuation-valid.html
      parsing/hanging-punctuation-invalid.html
    </wpt>

    <p>This property determines whether a punctuation mark, if one is present,
      <a>hangs</a> and may be placed outside the line box (or in the indent)
      at the start or at the end of a line of text.

    <p class="note">Note: If there is not sufficient padding on the
      block container, 'hanging-punctuation' can trigger overflow.</p>

    <p>When a glyph <dfn lt="hang">hangs</dfn>, it is not considered
      when measuring the line's contents for fit, alignment, or justification.
      Depending on the line's alignment/justification, this can
      result in the mark being placed outside the line box.
      (The interaction of this measurement and kerning is currently UA-defined;
      the CSSWG <a href="https://github.com/w3c/csswg-drafts/issues/2397">welcomes advice</a> on this point.)

    <p>Values have the following meanings:</p>

    <dl dfn-for=hanging-punctuation dfn-type=value>
      <dt><dfn>none</dfn></dt>
        <dd>No character <a>hangs</a>.</dd>
      <dt><dfn>first</dfn></dt>
        <dd>An opening bracket or quote at the start of the
          <a href="https://www.w3.org/TR/CSS2/selector.html#first-line-pseudo">first
          formatted line</a> of an element <a>hangs</a>.
          This applies to all characters in the Unicode categories Ps, Pf, Pi
          plus the ASCII quote marks “'” U+0027 and “"” U+0022.

          <wpt>
            hanging-punctuation/hanging-punctuation-first-001.xht
          </wpt>
      <dt><dfn>last</dfn></dt>
        <dd>A closing bracket or quote at the end of the
          last formatted line of an element <a>hangs</a>.
          This applies to all characters in the Unicode categories Pe, Pf, Pi
          plus the ASCII quote marks “'” U+0027 and “"” U+0022.

          <wpt>
            hanging-punctuation/hanging-punctuation-last-001.xht
          </wpt>
      <dt><dfn>force-end</dfn></dt>
        <dd>A <a>stop or comma</a> at the end of a line <a>hangs</a>.

        <wpt>
          hanging-punctuation/hanging-punctuation-force-end-001.xht
        </wpt>
        </dd>
      <dt><dfn>allow-end</dfn></dt>
        <dd>A <a>stop or comma</a> at the end of a line <a>hangs</a> if it
          does not otherwise fit prior to justification.

          <wpt>
            hanging-punctuation/hanging-punctuation-allow-end-001.xht
          </wpt>
        </dd>
    </dl>

    <p>Non-zero inline-axis borders or padding between
      a <a>hang</a>able mark and the edge of the line prevent the mark from hanging.
      For example, a period at the end of an inline box with end padding
      does not <a>hang</a> at the end edge of a line.
      At most one punctuation character may <a>hang</a> at each edge of the line.

    <p>A <a lt=hang>hanging</a> mark
      is still enclosed inside its parent inline box,
      is still counted as part of the <a>scrollable overflow region</a> [[!CSS-OVERFLOW-3]],
      and still participates in text justification:
      its character advance is just not measured when determining
      how much content fits on the line,
      how much the line's contents need to be expanded or compressed for justification,
      or how to position the content within the line box for text alignment.
      Effectively, the <a>hanging</a> glyph character advance
      is re-interpreted as an additional negative margin
      on the affected edge of its parent <a>inline box</a>;
      the line is otherwise laid out as usual.

      <wpt>
        hanging-punctuation/hanging-scrollable-001.html
      </wpt>

    <p><dfn lt="stop or comma">Stops and commas</dfn> allowed to <a>hang</a> include:
    <table class="data">
      <tr><td>U+002C <td>&#x002C; <td>COMMA
      <tr><td>U+002E <td>&#x002E; <td>FULL STOP
      <tr><td>U+060C <td>&#x060C; <td>ARABIC COMMA
      <tr><td>U+06D4 <td>&#x06D4; <td>ARABIC FULL STOP
      <tr><td>U+3001 <td>&#x3001; <td>IDEOGRAPHIC COMMA
      <tr><td>U+3002 <td>&#x3002; <td>IDEOGRAPHIC FULL STOP
      <tr><td>U+FF0C <td>&#xFF0C; <td>FULLWIDTH COMMA
      <tr><td>U+FF0E <td>&#xFF0E; <td>FULLWIDTH FULL STOP
      <tr><td>U+FE50 <td>&#xFE50; <td>SMALL COMMA
      <tr><td>U+FE51 <td>&#xFE51; <td>SMALL IDEOGRAPHIC COMMA
      <tr><td>U+FE52 <td>&#xFE52; <td>SMALL FULL STOP
      <tr><td>U+FF61 <td>&#xFF61; <td>HALFWIDTH IDEOGRAPHIC FULL STOP
      <tr><td>U+FF64 <td>&#xFF64; <td>HALFWIDTH IDEOGRAPHIC COMMA
    </table>
    <p>The UA may include other characters as appropriate.

    <p class="note">Note: The CSS Working Group would appreciate if UAs including
      other characters would <a href="#status">inform the working group</a>
      of such additions.</p>

    <div class="example">
      <p>The ''allow-end'' and ''force-end'' are two variations of
        hanging punctuation used in East Asia.</p>
      <div>
      <div class="sidefigure">
        <img src="images/hanging-punctuation-allow-end.png"
          width="202" height="51"
          alt="hanging-punctuation: allow-end">
      </div>
      <pre class="css">
        p {
          text-align: justify;
          hanging-punctuation: allow-end;
        }</pre>
      <div class="sidefigure">
        <img src="images/hanging-punctuation-force-end.png"
          width="202" height="51"
          alt="hanging-punctuation: force-end">
      </div>
      <pre class="css">
        p {
          text-align: justify;
          hanging-punctuation: force-end;
        }
      </pre>
      </div>
      <p>The punctuation at the end of the first line for ''allow-end''
        does not hang, because it fits without hanging.
        However, if ''force-end'' is used, it is forced to hang.
        The justification measures the line without the hanging punctuation.
        Therefore when the line is expanded, the punctuation is pushed outside the line.</p>
    </div>

<h3 id="bidi-linebox">
Bidirectionality and Line Boxes</h3>

  <p>The <a spec=css-writing-modes-3>start</a> and <a spec=css-writing-modes-3>end</a> edges of a line box
    are determined by the <a>inline base direction</a> of the line box.
    In most cases, this is given by its containing block's computed 'direction'.

  <p>However if its containing block has ''unicode-bidi: plaintext'' [[!CSS-WRITING-MODES-3]],
    the line box's <a>inline base direction</a> must be determined
    by the <a>inline base direction</a> of the <a>bidi paragraph</a> to which it belongs:
    that is, the <a>bidi paragraph</a> for which the line box holds content.
    An empty line box
    (i.e. one that contains no atomic inlines or
     characters other than the line-breaking character, if any),
    takes its <a>inline base direction</a> from the preceding line box (if any), or,
    if this is the first line box in the containing block,
    then from the 'direction' property of the containing block.

  <div class="example">
    <p>In the following example, assuming the <code>&lt;block&gt;</code>
    is a preformatted block (''display: block; white-space: pre'') inheriting
    ''text-align: start'', every other line is right-aligned:</p>
    <pre>
      &lt;block style="unicode-bidi: plaintext"&gt;
        Latin
        &#x0648;·&#x06A9;&#x0645;&#x06CC;
        Latin
        &#x0648;·&#x06A9;&#x0645;&#x06CC;
        Latin
        &#x0648;·&#x06A9;&#x0645;&#x06CC;
      &lt;/block&gt;</pre>
  </div>

  <p class="note">Note: The inline base direction determined here
    applies to the line box itself, and not to its contents.
    It affects 'text-align-all', 'text-align-last', 'text-indent', and 'hanging-punctuation',
    i.e. the position and alignment of its contents with respect to its edges.
    It does not affect the formatting or ordering of its content.

  <div class="example">
    <p>In the following example:
    <pre>
      &lt;para style="display: block; direction: rtl; unicode-bidi:plaintext">
      &lt;quote style="unicode-bidi:plaintext">שלום!&lt;/quote>", he said.
      &lt;/para&gt;</pre>

    <p>The result should be a left-aligned line looking like this:
    <pre>"!&#1513;&#1500;&#1493;&#1501;", he said.</pre>

    <p>The line is left-aligned
      (despite the containing block having ''direction: rtl'')
      because the containing block (the <code>&lt;para></code>) has ''unicode-bidi:plaintext'',
      and the line box belongs to a bidi paragraph that is LTR.
      This is because that paragraph's first character with a strong direction
      is the LTR "h" from "he". The RTL "שלום!" does precede the "he",
      but it sits in its own bidi-isolated paragraph that is <em>not</em>
      immediately contained by the <code>&lt;para&gt;</code>,
      and is thus irrelevant to the line box's alignment.
      From from the standpoint of the bidi paragraph immediately contained
      by the <code>&lt;para&gt;</code> containing block,
      the <code>&lt;quote&gt;</code>&rsquo;s bidi-isolated paragraph inside it is,
      by definition, just a neutral U+FFFC character,
      so the immediately-contained paragraph becomes LTR by virtue
      of the "he" following it.
  </div>

  <div class="example">
    <pre>
      &lt;fieldset style="direction: rtl">
      &lt;textarea style="unicode-bidi:plaintext">

      Hello!

      &lt;/textarea>
      &lt;/fieldset></pre>

    <p>As expected, the "Hello!" should be displayed LTR
      (i.e. with the exclamation mark on the right end,
      despite the <code>&lt;textarea></code>’s ''direction:rtl'')
      and left-aligned.
      This makes the empty line following it left-aligned as well,
      which means that the caret on that line should appear at its
      left edge. The first empty line, on the other hand, should
      be right-aligned, due to the RTL direction of its containing
      paragraph, the <code>&lt;textarea></code>.
  </div>

<h2 class="no-num" id="order">Appendix A:
Text Processing Order of Operations</h2>

  <p>The following list defines the order of text operations.
  (Implementations are not bound to this order as long as the resulting layout is the same.)

  <ol>
    <li><a href="#white-space-phase-1">white space processing</a> part I (pre-wrapping)
    <li><a href="#transforming">text transformation</a>
    <li><a href="https://www.w3.org/TR/css-writing-modes-3/#text-combine-horizontal">text combination</a>
    <li><a href="https://www.w3.org/TR/css-writing-modes-3/#text-orientation">text orientation</a> [[!CSS-WRITING-MODES-3]]
    <li><a href="#wrapping">text wrapping</a> while applying per line:
      <ul>
        <li><a href="#text-indent-property">indentation</a>
        <li><a href="https://www.w3.org/TR/css-writing-modes-3/#text-direction">bidirectional reordering</a> [[!CSS2]] / [[!CSS-WRITING-MODES-3]]
        <li><a href="#white-space-phase-2">white space processing</a> part II
        <li><a href="https://www.w3.org/TR/css-fonts-3/">font/glyph selection and positioning</a> [[!CSS2]] / [[!CSS-FONTS-3]]
        <li>'letter-spacing' and 'word-spacing'
        <li><a href="#hanging-punctuation-property">hanging punctuation</a>
      </ul>
    <li><a href="#justification">justification</a> (which may affect glyph selection and/or text wrapping, looping back into that step)
    <li><a href="#text-align-property">text alignment</a>
  </ol>

<h2 class="no-num" id="plaintext">
Appendix B: Conversion to Plaintext</h2>

  <p>This appendix is normative for the purpose of plaintext copy-paste operations.

  <!-- https://lists.w3.org/Archives/Public/www-style/2016Oct/0115.html
       https://lists.w3.org/Archives/Public/public-editing-tf/2016Apr/0005.html -->

  <p>When a CSS-rendered document is converted to a plaintext format,
  it is expected that:
  <ul>
    <li>The 'text-transform' property has no effect.
    <li>[[#white-space-phase-1]] is applied and any sequence of
        <a>collapsible</a> spaces at the beginning of a <a>block</a>
        or immediately following a <a>forced line break</a> is removed.
  </ul>

<h2 class="no-num" id="default-stylesheet">
Appendix C: Default UA Stylesheet</h2>

  <p>This appendix is informative,
  and is to help UA developers to implement a default stylesheet for HTML,
  but UA developers are free to ignore or modify as appropriate.

  <div class="example">
    <pre>
      /* make list items and option elements align together */
      li, option { text-align: match-parent; }</pre>
  </div>
  <p class="feedback issue">If you find any issues, recommendations to add, or corrections,
    please send the information to <a href="mailto:www-style@w3.org">www-style@w3.org</a>
    with <kbd>[css-text]</kbd> in the subject line.</p>

<h2 class="no-num" id="script-groups">
Appendix D: Scripts and Spacing</h2>

  <p><em>This appendix is normative.</em></p>

  <p>Typographic behavior varies somewhat by language, but varies drastically by writing system.
  	This appendix categorizes some common <a lt="Unicode script">scripts</a> in Unicode 6.0
    according to their justification and spacing behavior.
  	Category descriptions are descriptive, not prescriptive;
  	the determining factor is the prioritization of <a>justification opportunities</a>.

  <dl>
  	<dt><dfn>block scripts</dfn></dt>
  	<dd>CJK and by extension all Wide characters (see [[!UAX11]].)
  	  The following <a>Unicode scripts</a> are included:
      Bopomofo, Han, Hangul, Hiragana, Katakana, and Yi.
      Characters of the <a>East Asian Width property</a>
      <code>Wide</code> and <code>Fullwidth</code> are also included,
      but <code>Ambiguous</code> characters are included only if
      the <a>writing system</a> is
      <a for=writing-system>Chinese</a>, <a for=writing-system>Korean</a>, or <a for=writing-system>Japanese</a>.
  	<dt><dfn>clustered scripts</dfn></dt>
  	<dd>Clustered scripts have discrete units
      and break only at word boundaries,
      but do not use visible word separators.
      They prioritize stretching spaces,
      but comfortably admit inter-character spacing for justification.
  	  The clustered scripts include, but are not limited to, the following <a>Unicode scripts</a>:
      Khmer,
      Lao,
      Myanmar,
      New Tai Lue,
      Tai Le,
      Tai Tham,
      Tai Viet,
      Thai
  	<dt><dfn lt="cursive script">cursive scripts</dfn>
  	<dd>Cursive scripts do not admit gaps between their letters for either justification or 'letter-spacing'.
      The following <a>Unicode scripts</a> are included:
      Arabic,
      Mandaic,
      Mongolian,
      N'Ko,
      Phags Pa,
      Syriac
  </dl>
  <p>User agents should update this list as they update their Unicode support
    to handle as-yet-unencoded cursive scripts in future versions of Unicode,
    and are encouraged to ask the CSSWG to update this spec accordingly.

  <p class="issue">Should block and cluster scripts be merged?
  They have different tolerances for space-justification vs inter-character justification,
  but both admit both.

<h2 id="character-properties" class="no-num">Appendix E.
Characters and Properties</h2>

  <p>Unicode defines four code point-level properties that are referenced
    in CSS typesetting:
  <dl export>
    <dt><dfn lt="Unicode East Asian Width|East Asian Width property"><a href="http://www.unicode.org/reports/tr11/#Definitions">East Asian width property</a></dfn>
    <dd>Defined in [[!UAX11]] and given as the <code>East_Asian_Width</code> property
      in the Unicode Character Database [[!UAX44]].
    <dt><dfn lt="Unicode General Category|Unicode category|General Category"><a href="http://www.unicode.org/reports/tr44/#General_Category_Values">general category</a></dfn>
    <dd>Defined in [[!UAX44]] and given as the <code>General_Category</code> property
      in the Unicode Character Database [[!UAX44]].
    <dt><dfn lt="Unicode Script|Script property"><a href="http://www.unicode.org/reports/tr24/#Values">script property</a></dfn>
    <dd>Defined in [[!UAX24]] and given as the <code>Script</code> property
      in the Unicode Character Database [[!UAX44]].
      (UAs must include any ScriptExtensions.txt assignments in this mapping.)
    <dt><a href="http://www.unicode.org/reports/tr50/">Vertical Orientation</a>
    <dd>Defined in [[!UTR50]] as the Vertical_Orientation property
      and given in the UTR50 data file.
  </dl>

  <p>Unicode defines properties for individual code points, but sometimes
    it is necessary to determine the properties of a <a>typographic character unit</a>.
    For the purposes of CSS Text,
    the properties of a <a>typographic character unit</a> are given by
    the base character of its first <a>grapheme cluster</a>—except in two cases:
  <ul>
    <li><a>Grapheme clusters</a> formed with an Enclosing Mark (<code>Me</code>) of the Common script
    are considered to be Other Symbols (<code>So</code>) in the Common script.
    They are assumed to have the same Unicode properties as the Replacement Character U+FFFD.
    <li>Grapheme clusters</a> formed with a Space Separator (<code>Zs</code>) as the base
    are considered to be Modifier Symbols (<code>Sk</code>).
    They are assumed to have the same East Asian Width property as the base,
    but take their other properties from the first combining character in the sequence.
  </ul>

<h2 id="script-tagging" class="no-num">Appendix F.
Tagging Content by Writing System</h2>

	<p><em>This appendix is normative.</em></p>

	While most languages have a preferred writing system,
	many can also be transcribed into a different writing system.
	As a common example, most languages have at least one Latin transcription,
	and can thus be written in the Latin writing system.
	In these cases the document typically adopts the typographic conventions of the Latin writing system:
	for example Japanese “romaji” and Chinese Pinyin use Latin letters and word spaces,
	and follow Latin line-breaking and justification practices accordingly.
	As another example, historical ideographic Korean
	(<code>ko-Hani</code>)
	does not use word spaces,
	and should therefore be typeset as for Chinese.

	In [[HTML]] or any other <a>document language</a> using [[BCP47]] to identify the [=content language=],
	authors can indicate the use of an atypical writing system
	with script subtags.
	For example, to indicate use of the Latin writing system
	for languages which don't natively use it,
	the <code>-Latn</code> script subtag can be added,
	e.g. <code>ja-Latn</code> for Japanese romaji.
	Other subtags exist for other writing systems:
	see [[BCP47]], [[ISO15924]], and the <a href="http://unicode.org/iso15924/iso15924-codes.html">ISO15924 script tag registry</a>.
	Some common/historical examples follow:

	<div class="example">
		<dl>
			<dt><code>zh-Latn</code>
			<dd>Chinese, written in Latin transcription.
			<dt><code>ko-Hani</code>
			<dd>Korean, written in Hanja (Chinese ideographic characters).
			<dt><code>tr-Arab</code>
			<dd>Turkish, written in Arabic script.
			<dt><code>mn-Cyrl</code>
			<dd>Mongolian, written in Cyrillic.
			<dt><code>mn-Mong</code>
			<dd>Mongolian, written in traditional Mongolian script.
		</dl>
	</div>

	UAs should assume the most common writing system
	of the specified <a>content language</a>
	when choosing typographic behaviors
	such as line-breaking or justification strategies,
	but must not assume that writing system
	if the author has explicitly indicated a different one.
	If the UA has no language-specific knowledge
	of a particular language and writing system combination,
	it must use the typographic conventions of the specified writing system
	(assuming the conventions of a different language if necessary),
	not the conventions of that language in a different writing system,
	which would be inappropriate to the writing system used in this case.

        <wpt>
          writing-system/writing-system-font-001.html
          writing-system/writing-system-text-transform-001.html
          writing-system/writing-system-segment-break-001.html
          writing-system/writing-system-line-break-001.html
          writing-system/writing-system-line-break-002.html
        </wpt>

	The full correspondence between languages and their most common writing system
	is out of scope for this document.
	However, User Agents must assume at least the following:

	* If the [=content language=] is Chinese and the [=writing system=] is unspecified,
		or for any [=content language=] if the [=writing system=] to specified to be one of the ''Hant'', ''Hans'', ''Hani'', ''Hanb'', or ''Bopo'' [[ISO15924]] codes,
		then the [=writing system=] is <dfn noexport for=writing-system>Chinese</dfn>.
	* If the [=content language=] is Japanese and the [=writing system=] is unspecified,
		or for any [=content language=] if the [=writing system=] to specified to be one of the ''Jpan'', ''Hrkt'', ''Hira'' or ''Kana'' [[ISO15924]] codes,
		then the [=writing system=] is <dfn noexport for=writing-system>Japanese</dfn>.


                <wpt>
                  writing-system/writing-system-line-break-002.html
                  writing-system/writing-system-segment-break-001.html
                </wpt>
	* If the [=content language=] is Korean and the [=writing system=] is unspecified,
		or for any [=content language=] if the [=writing system=] to specified to be one of the ''Kore'', ''Hang'', or ''Jamo'' [[ISO15924]] codes,
		then the [=writing system=] is <dfn noexport for=writing-system>Korean</dfn>.
	* The [=writing system=] is only considered to be <dfn noexport for=writing-system lt='known | unknown'>unknown</dfn>
		if the [=content language=] itself is unknown,
		or if it explicitly indicates an unknown writing system.

		Note: Mere omission of the [=writing system=] information when the [=content language=] is specified
		means the that the [=writing system=] is implied, not unknown.

	More advice on language tagging can be found in
	the <a href="https://www.w3.org/International/core/">Internationalization Working Group</a>’s
	<a href="https://www.w3.org/International/articles/language-tags/">“Language tags in HTML and XML”</a>
	and <a href="https://www.w3.org/International/questions/qa-choosing-language-tags">“Choosing a Language Tag”</a>.

<h2 id="small-kana" class=no-num>Appendix G.
Small Kana Mappings</h2>
<style>
.pairs-table th {
  text-align: center;
}
</style>

  <div class="pairs-table">
  <table class=data>
   <caption>Small Kana Map to Full-size Kana</caption>

   <thead>
    <tr>
     <th scope=col><dfn noexport for=kana lt="small | small kana">Small</dfn>
     <th scope=col><dfn noexport for=kana lt="full-size |full-size kana">Full-size</dfn>

   <tbody title="Hiragana">
    <!-- Vowels (Hiragana) -->
    <tr>
     <td>&#x3041; U+3041
     <td>&#x3042; U+3042
    <tr>
     <td>&#x3043; U+3043
     <td>&#x3044; U+3044
    <tr>
     <td>&#x3045; U+3045
     <td>&#x3046; U+3046
    <tr>
     <td>&#x3047; U+3047
     <td>&#x3048; U+3048
    <tr>
     <td>&#x3049; U+3049
     <td>&#x304A; U+304A

    <!-- Consonant K (Hiragana) -->
    <tr>
     <td>&#x3095; U+3095
     <td>&#x304B; U+304B
    <!--
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    -->
    <tr>
     <td>&#x3096; U+3096
     <td>&#x3051; U+3051
    <!--
    <tr>
     <td>
     <td>
    -->

    <!-- Consonant T (Hiragana) -->
    <!--
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    -->
    <tr>
     <td>&#x3063; U+3063
     <td>&#x3064; U+3064
    <!--
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    -->

    <!-- Consonant Y (Hiragana) -->
    <tr>
     <td>&#x3083; U+3083
     <td>&#x3084; U+3084
    <!--
    <tr>
     <td>
     <td>
    -->
    <tr>
     <td>&#x3085; U+3085
     <td>&#x3086; U+3086
    <!--
    <tr>
     <td>
     <td>
    -->
    <tr>
     <td>&#x3087; U+3087
     <td>&#x3088; U+3088

    <!-- Consonant W (Hiragana) -->
    <tr>
     <td>&#x308E; U+308E
     <td>&#x308F; U+308F
    <!--
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    -->

   <tbody title="Katakana">
    <!-- Vowels (Katakana) -->
    <tr>
     <td>&#x30A1; U+30A1
     <td>&#x30A2; U+30A2
    <tr>
     <td>&#x30A3; U+30A3
     <td>&#x30A4; U+30A4
    <tr>
     <td>&#x30A5; U+30A5
     <td>&#x30A6; U+30A6
    <tr>
     <td>&#x30A7; U+30A7
     <td>&#x30A8; U+30A8
    <tr>
     <td>&#x30A9; U+30A9
     <td>&#x30AA; U+30AA

    <!-- Consonant K (Katakana) -->
    <tr>
     <td>&#x30F5; U+30F5
     <td>&#x30AB; U+30AB
    <!--
    <tr>
     <td>
     <td>
    -->
    <tr>
     <td>&#x31F0; U+31F0
     <td>&#x30AF; U+30AF
    <tr>
     <td>&#x30F6; U+30F6
     <td>&#x30B1; U+30B1
    <!--
    <tr>
     <td>
     <td>
    -->

    <!-- Consonant S (Katakana) -->
    <!--
    <tr>
     <td>
     <td>
    -->
    <tr>
     <td>&#x31F1; U+31F1
     <td>&#x30B7; U+30B7
    <tr>
     <td>&#x31F2; U+31F2
     <td>&#x30B9; U+30B9
    <!--
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    -->

    <!-- Consonant T (Katakana) -->
    <!--
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    -->
    <tr>
     <td>&#x30C3; U+30C3
     <td>&#x30C4; U+30C4
    <!--
    <tr>
     <td>
     <td>
    -->
    <tr>
     <td>&#x31F3; U+31F3
     <td>&#x30C8; U+30C8

    <!-- Consonant N (Katakana) -->
    <!--
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    -->
    <tr>
     <td>&#x31F4; U+31F4
     <td>&#x30CC; U+30CC
    <!--
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    -->

    <!-- Consonant H (Katakana) -->
    <tr>
     <td>&#x31F5; U+31F5
     <td>&#x30CF; U+30CF
    <tr>
     <td>&#x31F6; U+31F6
     <td>&#x30D2; U+30D2
    <tr>
     <td>&#x31F7; U+31F7
     <td>&#x30D5; U+30D5
    <tr>
     <td>&#x31F8; U+31F8
     <td>&#x30D8; U+30D8
    <tr>
     <td>&#x31F9; U+31F9
     <td>&#x30DB; U+30DB

    <!-- Consonant M (Katakana) -->
    <!--
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    -->
    <tr>
     <td>&#x31FA; U+31FA
     <td>&#x30E0; U+30E0
    <!--
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    -->

    <!-- Consonant Y (Katakana) -->
    <tr>
     <td>&#x30E3; U+30E3
     <td>&#x30E4; U+30E4
    <!--
    <tr>
     <td>
     <td>
    -->
    <tr>
     <td>&#x30E5; U+30E5
     <td>&#x30E6; U+30E6
    <!--
    <tr>
     <td>
     <td>
    -->
    <tr>
     <td>&#x30E7; U+30E7
     <td>&#x30E8; U+30E8

    <!-- Consonant R (Katakana) -->
    <tr>
     <td>&#x31FB; U+31FB
     <td>&#x30E9; U+30E9
    <tr>
     <td>&#x31FC; U+31FC
     <td>&#x30EA; U+30EA
    <tr>
     <td>&#x31FD; U+31FD
     <td>&#x30EB; U+30EB
    <tr>
     <td>&#x31FE; U+31FE
     <td>&#x30EC; U+30EC
    <tr>
     <td>&#x31FF; U+31FF
     <td>&#x30ED; U+30ED

    <!-- Consonant W (Katakana) -->
    <tr>
     <td>&#x30EE; U+30EE
     <td>&#x30EF; U+30EF
    <!--
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    -->

   <tbody title="Half-width Katakana">
    <!-- Vowels (hwid) -->
    <tr>
     <td>&#xFF67; U+FF67
     <td>&#xFF71; U+FF71
    <tr>
     <td>&#xFF68; U+FF68
     <td>&#xFF72; U+FF72
    <tr>
     <td>&#xFF69; U+FF69
     <td>&#xFF73; U+FF73
    <tr>
     <td>&#xFF6A; U+FF6A
     <td>&#xFF74; U+FF74
    <tr>
     <td>&#xFF6B; U+FF6B
     <td>&#xFF75; U+FF75

    <!-- Consonant T (hwid Katakana) -->
    <!--
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    -->
    <tr>
     <td>&#xFF6F; U+FF6F
     <td>&#xFF82; U+FF82
    <!--
    <tr>
     <td>
     <td>
    <tr>
     <td>
     <td>
    -->

    <!-- Consonant Y (hwid Katakana) -->
    <tr>
     <td>&#xFF6C; U+FF6C
     <td>&#xFF94; U+FF94
    <!--
    <tr>
     <td>
     <td>
    -->
    <tr>
     <td>&#xFF6D; U+FF6D
     <td>&#xFF95; U+FF95
    <!--
    <tr>
     <td>
     <td>
    -->
    <tr>
     <td>&#xFF6E; U+FF6E
     <td>&#xFF96; U+FF96
  </table>
  </div>

  <wpt>
    text-transform/text-transform-full-size-kana-001.html
    text-transform/text-transform-full-size-kana-002.html
    text-transform/text-transform-full-size-kana-003.html
    text-transform/text-transform-full-size-kana-004.html
    text-transform/text-transform-full-size-kana-005.html
    text-transform/text-transform-full-size-kana-006.html
    text-transform/text-transform-full-size-kana-007.html
  </wpt>

<h2 id="priv-sec" class="no-num">
Privacy and Security Considerations</h2>

  This specification introduces no new security considerations.

  This specification leaks the user's installed hyphenation and line-breaking dictionaries.

<h2 class="no-num" id="acknowledgements">
Acknowledgements</h2>

  <p>This specification would not have been possible without the help from:
  Ayman Aldahleh, Bert Bos, Tantek Çelik, James Clark, Emilio Cobos Álvarez, Stephen Deach, John Daggett,
  Martin Dürst,
  Laurie Anna Edlund, Ben Errez, Yaniv Feinberg, Arye Gittelman, Ian
  Hickson, Martin Heijdra, Richard Ishida, Masayasu Ishikawa,
  Michael Jochimsen, Eric LeVine, Ambrose Li, Håkon Wium Lie, Chris Lilley,
  Ken Lunde, Myles Maxfield, Nat McCully, IM Mincheol, Shinyu Murakami, Paul Nelson,
  Chris Pratley, Xidorn Quan, Marcin Sawicki,
  Arnold Schrijver, Rahul Sonnad, Alan Stearns, Michel Suignard, Takao Suzuki,
  Frank Tang, Chris Thrasher, Etan Wexler, Chris Wilson, Masafumi Yabe
  and Steve Zilles.

<h2 class="no-num" id="changes">
Changes</h2>

  <h3 class="no-num" id="changes-2018-12-12" oldids="recent-changes">
  Changes from the <a href="https://www.w3.org/TR/2018/WD-css-text-3-20181212/">12 December 2018 Working Draft</a></h3>

  * Clarify that ''hyphens: none'' does not suppress wrapping opportunities after U+002D or U+2010.
  * Fix stray text leftover when removing percentages as a possible value for word-spacing.
  * Add support for ''word-break: break-word'' as a deprecated value, as needed for compatibility with this previously proprietary syntax.
  * Use ''allow-end'' hanging rules rather than ''force-end'' rules for trailing white space;
    define how it impacts intrinsic size contributions of text.
    (<a href="https://github.com/w3c/csswg-drafts/issues/3440">Issue 3440</a>)

  <h3 class="no-num" id="changes-2018-12-06">
  Changes from the <a href="https://www.w3.org/TR/2018/WD-css-text-3-20181206/">6 December 2018 Working Draft</a></h3>

  Changes between 6 December 2018 and 12 December 2018 consist of
  some minor cleanup in the line breaking section
  and deferring <<percentage>> values of 'word-spacing' to Level 4
  with the expectation that they will be redefined
  (see discussion in <a href="https://github.com/w3c/csswg-drafts/issues/2165">issue 2165</a>).

  <h3 class="no-num" id="changes-2013">
  Changes from the <a href="https://www.w3.org/TR/2013/WD-css-text-3-20131010/">October
  2013 CSS3 Text <abbr title="Last Call Working Draft">LCWD</abbr></a></h3>

  ISSUE: THIS CHANGES LIST IS WAY INCOMPLETE PLEASE SEE
  <a href="https://drafts.csswg.org/css-text-3/issues-lc-2013">Disposition of Comments</a>.

  <ul>
    <li>Switched 'tab-size' to use <<number>> so that it is animatable,
        and defined it to also account for 'letter-spacing' and 'word-spacing'.
    <li>Made 'text-align' a shorthand of 'text-align-last' and the new 'text-align-all' property.
    <li>Removed dependence of 'text-align-last' on ''text-align: justify'',
        since the problem it solves is now solved by the shorthanding relationship.
    <li>Qualified that only lowercase letters are titlecased for ''text-transform: capitalize''; uppercase letters remain unaffected.
    <li>For ''word-break: break-all'', switched to UAX14 notion of “letters”,
        since that handles symbols better.
    <li>Added ''line-break: anywhere'' and ''overflow-wrap: anywhere''.
    <li>Tweaked handling of Ambiguous characters during <a href="#line-break-transform">segment break transformation</a> to respond to language context.
  </ul>