[css-text-3] Add appendix on language tagging, explain its relationship to writing system and typographic conventions, and make this information more prominent. Fixes w3c#2015 and fixes w3c#1015.

fantasai · fantasai · commit c983ca60b3a2 · 2018-03-22T18:55:24.000-07:00
diff --git a/css-text-3/Overview.bs b/css-text-3/Overview.bs
@@ -2,7 +2,7 @@
 Title: CSS Text Module Level 3
 Shortname: css-text
 Level: 3
-Status: WD
+Status: ED
 Work Status: Refining
 Group: csswg
 ED: https://drafts.csswg.org/css-text-3/
@@ -138,6 +138,10 @@ Module Interactions</h3>
   <p>This module, together with [[CSS3-TEXT-DECOR]],
   replaces and extends the text-level features defined in [[!CSS21]] chapter 16.
 
+  <p>In addition to the terms defined below,
+    other terminology and concepts used in this specification are defined
+    in [[!CSS21]] and [[!CSS3-WRITING-MODES]].
+
 <h3 id="values">
 Values</h3>
 
@@ -150,15 +154,38 @@ Values</h3>
   also accept the <a>CSS-wide keywords</a> keywords as their property value.
   For readability they have not been repeated explicitly.
 
-<h3 id="terms">
-Terminology</h3>
+<h3 id="languages">
+Languages and Typesetting</h3>
 
-  <p>In addition to the terms defined below,
-    other terminology and concepts used in this specification are defined
-    in [[!CSS21]] and [[!CSS3-WRITING-MODES]].
+  <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/CSS21/conform.html#doclanguage">document language</a>.
+    For example, the rules for determining the <a>content language</a> of an HTML
+    element use the <code>lang</code> attribute and are defined in [[HTML5]],
+    and the rules for determining the <a>content language</a> of an XML element use
+    the <code>xml:lang</code> attribute and 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.
 
-<h4 id="characters">
-Characters and Letters</h4>
+    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
+    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,
@@ -274,29 +301,6 @@ Characters and Letters</h4>
   Authors are forewarned that dividing <a>grapheme clusters</a>
   by element boundaries may give inconsistent or undesired results.
 
-<h4 id="languages">
-Languages and Typesetting</h4>
-
-  <p class="note">
-    Many typographic effects vary by linguistic context.
-    In CSS, language-specific typographic tailorings
-    are only applied when the content language is known (declared).
-
-  <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/CSS21/conform.html#doclanguage">document language</a>.
-    For example, the rules for determining the <a>content language</a> of an HTML
-    element use the <code>lang</code> attribute and are defined in [[HTML5]],
-    and the rules for determining the <a>content language</a> of an XML element use
-    the <code>xml:lang</code> attribute and 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.
-
 <h2 id="transforming">
   Transforming Text</h2>
 
@@ -2381,6 +2385,64 @@ Characters and Properties</h2>
     but take their other properties from the first combining character in the sequence.
   </ul>
 
+<h2 id="script-tagging" class="no-num">Appendix E.
+Tagging Content by Writing System</h2>
+
+	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.
+
+	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.
+
+	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="priv-sec" class="no-num">
 Privacy and Security Considerations</h2>
 
diff --git a/css-text-3/issues-lc-2013.html b/css-text-3/issues-lc-2013.html
@@ -965,7 +965,7 @@ <h1>CSS Text Level 3 Disposition of Comments for 2013-10-10 LCWD</h1>
 <span>Response: <a href='https://lists.w3.org/Archives/Public/www-style/2017Jan/0021.html'>https://lists.w3.org/Archives/Public/www-style/2017Jan/0021.html</a> <a href="https://www.w3.org/Mail/flatten/index?subject=https%3A%2F%2Flists.w3.org%2FArchives%2FPublic%2Fwww-style/2017Jan/0021.html"><abbr title="Thread">&#x2208;</abbr></a></span>
 <span>Testcase: <a href='http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%0A%3Cdiv%20style%3D%22font-family%3A%20monospace%3B%20width%3A%20-moz-min-content%3B%20width%3A%20min-content%3B%20border%3A%20solid%20silver%3B%20white-space%3A%20pre-line%22%3Ea%20%0Ab%20c'>http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%0A%3Cdiv%20style%3D%22font-family%3A%20monospace%3B%20width%3A%20-moz-min-content%3B%20width%3A%20min-content%3B%20border%3A%20solid%20silver%3B%20white-space%3A%20pre-line%22%3Ea%20%0Ab%20c</a></span>
 <span class="r">Open:     Rejected</span>
-<span class="a">Verified: =Tab= Verify</span></pre>
+<span class="a">Verified: via IRC</span></pre>
 <pre class=' a' id='issue-107'>
 <span>Issue 107. <a href='#issue-107'>#</a></span>
 <span>Summary:  unbreakable “word” underdefined</span>
@@ -1229,12 +1229,13 @@ <h1>CSS Text Level 3 Disposition of Comments for 2013-10-10 LCWD</h1>
 <span>From:     Manishearth</span>
 <span>Comment:  <a href='https://github.com/w3c/csswg-drafts/issues/866'>https://github.com/w3c/csswg-drafts/issues/866</a></span>
 <span class="">Open:     =WG= Discuss.</span></pre>
-<pre class='open ' id='issue-140'>
+<pre class=' a' id='issue-140'>
 <span>Issue 140. <a href='#issue-140'>#</a></span>
 <span>Summary:  Add lang tagging guidance as an appendix</span>
 <span>From:     fantasai</span>
 <span>Comment:  <a href='https://github.com/w3c/csswg-drafts/issues/1015'>https://github.com/w3c/csswg-drafts/issues/1015</a></span>
-<span class="">Open:     Needs Edits</span></pre>
+<span class="a">Closed:   Accepted</span>
+<span>Resolved: Editor discretion</span></pre>
 <pre class=' a' id='issue-141'>
 <span>Issue 141. <a href='#issue-141'>#</a></span>
 <span>Summary:  Can tab-size be zero?</span>
@@ -1413,12 +1414,12 @@ <h1>CSS Text Level 3 Disposition of Comments for 2013-10-10 LCWD</h1>
 <span>Comment:  <a href='https://github.com/w3c/csswg-drafts/issues/2003'>https://github.com/w3c/csswg-drafts/issues/2003</a></span>
 <span>Response: <a href='https://github.com/w3c/csswg-drafts/issues/2003#issuecomment-370652901'>https://github.com/w3c/csswg-drafts/issues/2003#issuecomment-370652901</a></span>
 <span class="">Open:     =WG= Confirm.</span></pre>
-<pre class='open ' id='issue-164'>
+<pre class=' a' id='issue-164'>
 <span>Issue 164. <a href='#issue-164'>#</a></span>
 <span>Summary:  Intro about typographic dependency on lang forgets dep on writing system</span>
 <span>From:     fantasai</span>
 <span>Comment:  <a href='https://github.com/w3c/csswg-drafts/issues/2015'>https://github.com/w3c/csswg-drafts/issues/2015</a></span>
-<span class="">Open:     Needs edits</span>
+<span class="a">Closed:   Accepted</span>
 <span>Resolved: Bugfix</span></pre>
 <pre class='open ' id='issue-165'>
 <span>Issue 165. <a href='#issue-165'>#</a></span>
diff --git a/css-text-3/issues-lc-2013.txt b/css-text-3/issues-lc-2013.txt
@@ -933,7 +933,7 @@ Response: https://lists.w3.org/Archives/Public/www-style/2016Aug/0057.html
 Response: https://lists.w3.org/Archives/Public/www-style/2017Jan/0021.html
 Testcase: http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%0A%3Cdiv%20style%3D%22font-family%3A%20monospace%3B%20width%3A%20-moz-min-content%3B%20width%3A%20min-content%3B%20border%3A%20solid%20silver%3B%20white-space%3A%20pre-line%22%3Ea%20%0Ab%20c
 Open:     Rejected
-Verified: =Tab= Verify
+Verified: via IRC
 ----
 Issue 107.
 Summary:  unbreakable “word” underdefined
@@ -1202,7 +1202,8 @@ Issue 140.
 Summary:  Add lang tagging guidance as an appendix
 From:     fantasai
 Comment:  https://github.com/w3c/csswg-drafts/issues/1015
-Open:     Needs Edits
+Closed:   Accepted
+Resolved: Editor discretion
 ----
 Issue 141.
 Summary:  Can tab-size be zero?
@@ -1386,7 +1387,7 @@ Issue 164.
 Summary:  Intro about typographic dependency on lang forgets dep on writing system
 From:     fantasai
 Comment:  https://github.com/w3c/csswg-drafts/issues/2015
-Open:     Needs edits
+Closed:   Accepted
 Resolved: Bugfix
 ----
 Issue 165.
