[css2] descriptions of font-* properties rewritten to show theyt are describing desired apearance not describing fonts (which may be used to produce the desired apprearance). Examples added for system fonts , and clarifying text

svgeesus · svgeesus · commit 2063b0db031b · 1998-02-21T03:48:39.000Z
--HG--
extra : convert_revision : svn%3A73dc7c4b-06e6-40f3-b4f7-9ed1dbc14bfc/trunk%401050
diff --git a/css2/fonts.src b/css2/fonts.src
@@ -1,6 +1,6 @@
 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
 <html lang="en">
-<!-- $Id: fonts.src,v 2.11 1998-02-21 00:11:19 ijacobs Exp $ -->
+<!-- $Id: fonts.src,v 2.12 1998-02-21 03:48:39 clilley Exp $ -->
 <HEAD>
 <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
 <TITLE>Fonts</TITLE>
@@ -109,32 +109,49 @@ selection</a>.
 <dl>
 <dt><strong><a name="font-family">Font family</a></strong>
 
-<dd>A <span class="index-def" title="font family"> font family</span>
-is a group of fonts that resemble one another.  One member of the
-family may be italic, another bold, another bold and italic,
-etc. Examples of font family names include Helvetica, New Century
-Schoolbook, and Kyokasho ICA L. Font families may be grouped into different
-categories: those with or without serifs, those whose characters are
-or are not proportionally spaced, those that resemble handwriting,
-those that are fantasy fonts, etc.
-
-<!-- Is it necessary to say this? "Font family names are not restricted to
-Latin characters." -->
-
-<dt><strong><a name="font-style">Font style</a></strong>
-<dd>The font style specifies whether the specified font is normal,
-	  italic, or oblique (italic and oblique fonts are similar,
-	  but not the same, especially for fonts with serifs).
+      <dd>A <span class="index-def" title="font family"> font
+      family</span> is a group of fonts that resemble one another and
+      are designed to be used in combination.  One member of the
+      family may be italic, another bold, another bold and italic,
+      etc. Examples of font family names include Helvetica, New
+      Century Schoolbook, and Kyokasho ICA L. Font family names are
+      not restricted to Latin characters.  Font families may be
+      grouped into different categories: those with or without serifs,
+      those whose characters are or are not proportionally spaced,
+      those that resemble handwriting, those that are fantasy fonts,
+      etc.
+
+
+<dt><strong><a name="font-style">Font style</a></strong> 
+
+      <dd>The font style specifies whether the text is to be rendered
+      using a normal, italic, or oblique face. Italic is a more
+      cursive companion face to the normal face, but not so cursive as
+      to make it a script face. Oblique is a slanted form of the
+      normal face, and is more commonly used as a companion face to
+      sans-serif.
+
 <dt><strong><a name="font-variant">Font variant</a></strong>
-<dd>The font variant indicates whether the font contains normal upper
-	  and lowercase characters or whether it contains small-caps
-	  characters. 
+
+      <dd>The font variant indicates whether the text is to be
+      rendered using the normal glyphs for lowercase characters or
+      using small-caps glyphs for lowercase characters. (A particular
+      font may contain only normal, only small-caps, or both types of
+      glyph)
+
 <dt><strong><a name="font-weight">Font weight</a></strong>
-<dd>The font weight refers to the boldness or lightness of a font's
-glyphs.
+
+      <dd>The font weight refers to the boldness or lightness of a font's
+	glyphs relative to others in the same family.
+
 <dt><strong><a name="font-size">Font size</a></strong>
-<dd>The font size refers to the size of the font.
-<!-- Be more specific about size -IJ -->
+
+      <dd>The font size refers to the size of the font from baseline
+      to baseline, when set solid (in CSS terms, this is when the
+      <span class="propinst-font-size">'font-size'</span> and <span
+      class="propinst-line-height">'line-height'</span> properties
+      have the same value).
+
 </dl>
 
 
@@ -146,8 +163,11 @@ refer to the font size of the parent element. Please consult the
 section on <a href="./syndata.html#length-units">length units</a> for
 more information.
 
-<P>For information about the classification of fonts in general,
-please consult the section on <a
+<p>The font properties in CSS are used to describe the desired
+appearance of text in the document. The font descriptors, in contrast,
+are used to describe the characteristics of fonts, so that a suitable
+font can be chosen to create the desired appearance. For information
+about the classification of fonts, please consult the section on <a
 href="#font-descriptors">font descriptors</a>.
 
 
@@ -159,9 +179,10 @@ class="propinst-font-family">'font-family'</span></H3>
 <P>This property specifies a prioritized list of font family names
 and/or generic family names. To deal with the problem that a single
 font may not contain glyphs to display all the characters in a
-document, this property allows authors to specify a list of fonts, all
-of the same style and size, that are tried in sequence to see if they
-contain a glyph for a certain character. This list is called a <span
+document, or that not all fonts are available on all systems, this
+property allows authors to specify a list of fonts, all of the same
+style and size, that are tried in sequence to see if they contain a
+glyph for a certain character. This list is called a <span
 class="index-def" title="font set"><dfn>font set</dfn></span>.
 
 <div class="example"><P>
@@ -281,9 +302,9 @@ However, emphasized text (EM) within an H1 will appear in a normal face.
 
 <!-- #include src=properties/font-variant.srb -->
 
-<P>In a small-caps font, the lowercase letters look similar to the
-uppercase ones, but in a smaller size and with slightly different
-proportions. The <span
+<P>In a small-caps font, the glyphs for lowercase letters look similar
+to the uppercase ones, but in a smaller size and with slightly
+different proportions. The <span
 class="propinst-font-variant">'font-variant'</span> property selects
 that font. This property has no visible effect for scripts which are
 unicameral (having only one case). Values have the following
@@ -314,11 +335,10 @@ with emphasized words (EM) in oblique small-caps:
 </PRE>
 </div>
 
-<P> There may be other variants in the font family as well, such as
+<!-- There may be other variants in the font family as well, such as
 fonts with old-style numerals, small-caps numerals, condensed or
-expanded letters, etc. CSS2 does offer <span
-class="propinst-font-variant">'font-variant'</span> values that select
-those variants.
+expanded letters, etc. CSS2 does not offer 'font-variant' values that select
+those variants. -->
 
 <P>Insofar as this property causes text to be transformed to
 uppercase, the same considerations as for <span
@@ -360,7 +380,8 @@ the next lighter numerical value (and keeps the font unchanged).
 </PRE>
 </div>
 
-<!-- I added the above example, please verify -IJ -->
+<!-- I added the above example, please verify IJ 
+    seems fine, CL -->
 
 <P>Child elements inherit the <a href="cascade.html#computed-value">
 computed value</a> of the weight.
@@ -482,9 +503,10 @@ are:
 
     <P> [ xx-small | x-small | small | medium | large | x-large | xx-large ]
 
-    <P>On a computer screen a scaling factor of 1.5 is suggested
-    between adjacent indexes; if the 'medium' font is 10pt, the
-    'large' font could be 15pt. Different media may need different
+    <P>On a computer screen a scaling factor of 1.2 <!-- changed from
+    1.5 which was widely criticised as far too much, CL -->is
+    suggested between adjacent indexes; if the 'medium' font is 10pt,
+    the 'large' font could be 12pt. Different media may need different
     scaling factors. Also, the user agent should take the quality and
     availability of fonts into account when computing the table. The
     table may be different from one font family to another.
@@ -522,8 +544,10 @@ of"><strong>&lt;relative-size&gt;</strong></span>
 <P>The <a href="cascade.html#computed-value">computed value</a> of
 this property may differ from the <a
 href="cascade.html#specified-value">specified value</a> according to
-context. For example, inside a virtual reality scene the user agent
-may compute a different size because of perspective distortion.</P>
+context. <!-- bad example: For example, inside a virtual reality scene
+the user agent may compute a different size because of perspective
+distortion.-->
+
 
 <div class="example"><P>
 <P> Examples:
@@ -538,16 +562,17 @@ may compute a different size because of perspective distortion.</P>
 
 <!-- #include src=properties/font-size-adjust.srb -->
 
-<P>The subjective apparent size (and general character of a font on
-screen) is less dependent on its <a
+<P>In bicameral scripts, the subjective apparent size (and general
+character of a font on screen) is less dependent on its <a
 href="syndata.html#em-height">em-height</a> than on the size of its <a
-href="syndata.html#x-height">x-height</a>, or, more usefully, on its
-<span class="index-def" title="z value"><dfn>z value</dfn></span>. The
-lower the z value, the more likely it is that a font at smaller em sizes
-will be legible. Inversely, faces with a higher z value will become
-illegible more rapidly below a given threshold size than faces with a
-lower z value. Straightforward font substitution that relies on em- or
-x-height alone may lead to illegible characters.
+href="syndata.html#x-height">x-height</a>, or, more usefully, on the
+ratio of these two values, called the <span class="index-def" title="z
+value"><dfn>z value</dfn></span> (x-height divided by em-height. The
+lower the z value, the more likely it is that a font at smaller em
+sizes will be legible. Inversely, faces with a higher z value will
+become illegible more rapidly below a given threshold size than faces
+with a lower z value. Straightforward font substitution that relies on
+em- or x-height alone may lead to illegible characters.
 
 <P>For example, the popular font Verdana has a z value of 1.72; in an
 instance of Verdana at 100 points (<a
@@ -584,7 +609,7 @@ according to the following formula:
 </dl>
 
 <P>The first image below shows several typefaces as rasterized on a
-Macintosh at 12 point, together with their z values. No matter what
+Macintosh at 12-point, together with their z values. No matter what
 the typographical family (or nominal base size, unit, or platform),
 faces with lower z values look bigger than those with higher z values.
 Faces with very high z values are illegible at the size shown.</p>
@@ -594,7 +619,7 @@ Faces with very high z values are illegible at the size shown.</p>
 <P>The next image shows the results of <span
 class="propinst-font-size-adjust">'font-size-adjust'</span> with the
 fonts shown in the previous image. These fonts' em sizes range all the
-way up to '25pt', but appear subjectively to be about as large as
+way up to 25-point, but appear subjectively to be about as large as
 12-point Verdana, whose z value served as the base for scaling. As
 adjusted, the legibility characteristics of these faces on screen are
 nearly linear across faces. Note that <span
@@ -615,42 +640,13 @@ class="propinst-font-weight">'font-weight'</span>, <span
 class="propinst-font-size">'font-size'</span>, <span
 class="propinst-line-height">'line-height'</span>, and <span
 class="propinst-font-family">'font-family'</span>, at the same place
-in the style sheet. The syntax of this property is based on a
-traditional typographical shorthand notation to set multiple
-properties related to fonts.
+in the style sheet. <!-- but not font-size-adjust --> The syntax of
+this property is based on a traditional typographical shorthand
+notation to set multiple properties related to fonts.
 
 <P> For a definition of allowed and initial values, see the previously
 defined properties. A sub-property for which no value is given
-takes its initial value.
-
-<P>The following values refer to <span class="index-def" title="system
-fonts">system fonts</span>:</p>
-
-<dl>
-<dt><strong>caption</strong>
-<dd>Used for (captioned controls (e.g. buttons, drop-downs, etc.).
-<dt><strong>icon</strong>
-<dd> Used to label icons.
-<dt><strong>menu</strong>
-<dd> Used in menus (e.g., dropdown menus and menu lists).
-<dt><strong>message-box</strong>
-<dd> Used in dialog boxes.
-<dt><strong>small-caption</strong>
-<dd> Used for labeling small controls.
-<dt><strong>status-bar</strong>
-<dd> Used in window status bars.
-</dl>
-
-<P>System fonts may only be accessed as a whole; that is, the font
-family, size, weight, style, etc. are all set at the same time. If no
-font with the indicated characteristics exists on a given platform,
-the user agent should either intelligently substitute (e.g., a smaller
-version of the 'caption' font might be used for the 'smallcaption'
-font), or substitute a user agent default font. As for regular fonts,
-if, for a system font, any of the individual properties are not part
-of the operating system's available user preferences, those properties
-should be set to their initial values.
-
+is reset to its initial value, <em>not</em> the inherited value.
 
 <div class="example"><P>
 Examples:
@@ -660,8 +656,6 @@ Examples:
   P { font: x-large/110% "new century schoolbook", serif }
   P { font: bold italic large Palatino, serif }
   P { font: normal small-caps 120%/120% fantasy }
-  P { font: messagebox }
-  INPUT.small { font: smallcaption }
 </PRE>
 
 <P> In the second rule, the font size percentage value ('80%') refers
@@ -689,10 +683,70 @@ remaining properties: <span
 class="propinst-font-style">'font-style'</span> and <span
 class="propinst-font-weight">'font-weight'</span>.
 
-<P>The sixth and seventh rules set the font properties to the
-appropriate values for these elements in the user's environment.
 </div>
 
+<P>The following values refer to <span class="index-def" title="system
+fonts">system fonts</span>:</p>
+
+<dl>
+<dt><strong>caption</strong>
+<dd>Used for (captioned controls (e.g. buttons, drop-downs, etc.).
+<dt><strong>icon</strong>
+<dd> Used to label icons.
+<dt><strong>menu</strong>
+<dd> Used in menus (e.g., dropdown menus and menu lists).
+<dt><strong>message-box</strong>
+<dd> Used in dialog boxes.
+<dt><strong>small-caption</strong>
+<dd> Used for labeling small controls.
+<dt><strong>status-bar</strong>
+<dd> Used in window status bars.
+</dl>
+
+<P>System fonts can only be accessed as a whole; that is, the font
+family, size, weight, style, etc. are all set at the same time from
+the values used by that system font. These values may then be altered
+individually if desired. As for regular fonts, if, for a system font,
+any of the individual properties are not part of the operating
+system's available user preferences, those properties should be set to
+their initial values.
+
+<div class="example">
+<p>Example:
+
+<pre>
+  BUTTON { font: 300 italic 1.3em/1.7em "FB Armada", sans-serif }
+  BUTTON P { font: menu }
+  BUTTON P EM { font-weight: bolder }
+<pre>
+
+<p>If the font used for dropdown menus on a particular system
+happended to be 9-point Charcoal, with a weight of 600, then P
+elements which were descendents of BUTTON would be displayed as if
+this rule were in effect (the values for the remaining properties
+being taken from the initial values):
+
+<pre>
+  BUTTON P {
+    font-style: normal;
+    font-variant: normal;
+    font-weight: 600;
+    font-size: 9pt;
+    line-height: normal;
+    font-family: Charcoal
+  } stuff
+
+</div>
+
+
+<p>If no font with the indicated characteristics exists on a given
+platform, the user agent should either intelligently substitute (e.g.,
+a smaller version of the 'caption' font might be used for the
+'smallcaption' font), or substitute a user agent default font. 
+
+
+
+
 
 <h3><a name="generic-font-families">Generic font families</a></h3>
 
