Tweak attr() wording in some places, and speciy computed value better.

Author: tabatkins

css3-values/Overview.html

@@ -1605,7 +1605,7 @@ <h3 id=attr><span class=secno>8.3. </span> Attribute References: &lsquo;<a
   http://lists.w3.org/Archives/Member/w3c-css-wg/2002OctDec/0141.html
 -->
 
-  <p>The <dfn id=attr-value>attr()</dfn> function returns the value of an
+  <p>The <dfn id=attr-value>attr()</dfn> function can return the value of an
    attribute on the element for use as a value in a property. If used on a
    pseudo-element, it returns the value of the attribute on the
    pseudo-element's originating element.
@@ -1616,8 +1616,8 @@ <h3 id=attr><span class=secno>8.3. </span> Attribute References: &lsquo;<a
    href="#attr-value"><code class=css>attr()</code></a>&rsquo; expression can
    return many different types. The &lsquo;<a href="#attr-value"><code
    class=css>attr()</code></a>&rsquo; expression cannot return everything,
-   for example it cannot do counters, named strings, quotes, or values such
-   as &lsquo;<code class=css>auto</code>&rsquo;, &lsquo;<code
+   for example it cannot do counters, named strings, quotes, or keyword
+   values such as &lsquo;<code class=css>auto</code>&rsquo;, &lsquo;<code
    class=css>nowrap</code>&rsquo;, or &lsquo;<code
    class=css>baseline</code>&rsquo;. This is intentional, as the intent of
    the &lsquo;<a href="#attr-value"><code class=css>attr()</code></a>&rsquo;
@@ -1640,28 +1640,27 @@ <h3 id=attr><span class=secno>8.3. </span> Attribute References: &lsquo;<a
    the value of the attribute with that name on the element, according to the
    rules given below.
 
-  <p>The &lsquo;<code class=css>&lt;type></code>&rsquo; argument (which is
-   optional) is a keyword drawn from the list below that tells the UA how to
-   interpret the attribute value. If omitted, &lsquo;<code
-   class=css>string</code>&rsquo; is implied. If the type is not valid for
-   where the &lsquo;<a href="#attr-value"><code
-   class=css>attr()</code></a>&rsquo; expression is placed, the whole
-   &lsquo;<a href="#attr-value"><code class=css>attr()</code></a>&rsquo;
-   expression is invalid.
+  <p>The optional &lsquo;<code class=css>&lt;type></code>&rsquo; argument is
+   a keyword drawn from the list below that tells the UA how to interpret the
+   attribute value. If omitted, &lsquo;<code class=css>string</code>&rsquo;
+   is implied. If the type is not valid for where the &lsquo;<a
+   href="#attr-value"><code class=css>attr()</code></a>&rsquo; expression is
+   placed, the whole &lsquo;<a href="#attr-value"><code
+   class=css>attr()</code></a>&rsquo; expression is invalid.
 
-  <p>The &lsquo;<code class=css>&lt;value></code>&rsquo; argument (which is
-   optional) is a CSS value which must be valid where the &lsquo;<a
+  <p>The optional &lsquo;<code class=css>&lt;value></code>&rsquo; argument is
+   a CSS value which must be valid where the &lsquo;<a
    href="#attr-value"><code class=css>attr()</code></a>&rsquo; expression is
-   placed. It represents a fallback value to be used if the named attribute
-   is missing, or its value cannot be parsed into the given type or is
-   invalid/out-of-range for the property. If the &lsquo;<code
+   placed. It represents a fallback value, which is used if the named
+   attribute is missing, or its value cannot be parsed into the given type or
+   is invalid/out-of-range for the property. If the &lsquo;<code
    class=css>&lt;value></code>&rsquo; argument is not valid for the property
    where the &lsquo;<a href="#attr-value"><code
    class=css>attr()</code></a>&rsquo; expression is placed, the whole
    &lsquo;<a href="#attr-value"><code class=css>attr()</code></a>&rsquo;
-   expression is invalid. The fallback value must not be another &lsquo;<a
-   href="#attr-value"><code class=css>attr()</code></a>&rsquo; expression; if
-   it is, the outer &lsquo;<a href="#attr-value"><code
+   expression is invalid. The fallback value must not contain another
+   &lsquo;<a href="#attr-value"><code class=css>attr()</code></a>&rsquo;
+   expression; if it is, the outer &lsquo;<a href="#attr-value"><code
    class=css>attr()</code></a>&rsquo; expression is invalid. If the fallback
    &lsquo;<code class=css>&lt;value></code>&rsquo; is absent, the default
    value for the given type (from the list below) is implied.
@@ -1734,7 +1733,8 @@ <h3 id=attr><span class=secno>8.3. </span> Attribute References: &lsquo;<a
     relevant units is not valid for the property. The default should also be
     used if the property in question only accepts values within a certain
     range (e.g. positive lengths or angles from 0 to 90deg) and the attribute
-    is out of range (e.g. a negative length or 180deg).
+    is out of range (e.g. a negative length or 180deg). If the unit is a
+    relative length, it must be computed to an absolute length.
 
    <dt>&lsquo;<a href="#em-unit"><code class=css>em</code></a>&rsquo;
 
@@ -1781,7 +1781,8 @@ <h3 id=attr><span class=secno>8.3. </span> Attribute References: &lsquo;<a
     unit. The default is &lsquo;<code class=css>0</code>&rsquo; in the
     relevant units, or else the property's minimum value if &lsquo;<code
     class=css>0</code>&rsquo; in the relevant units is not valid for the
-    property.
+    property. If the unit is a relative length, it must be computed to an
+    absolute length.
   </dl>
 
   <div class=example>

css3-values/Overview.src.html

@@ -1120,14 +1120,14 @@ <h3 id="attr">
   http://lists.w3.org/Archives/Member/w3c-css-wg/2002OctDec/0141.html
 -->
 
-	<p>The <dfn id='attr-value'>attr()</dfn> function returns the value of an attribute on the element 
+	<p>The <dfn id='attr-value'>attr()</dfn> function can return the value of an attribute on the element 
 	for use as a value in a property.  If used on a pseudo-element, it returns 
 	the value of the attribute on the pseudo-element's originating element.</p>
 
 	<p>In CSS2.1 [[!CSS21]], the ''attr()''	expression always returns a	string. 
 	In CSS3, the ''attr()'' expression can return many different types. The 
 	''attr()'' expression cannot return everything, for example it cannot
-	do counters, named strings, quotes, or values such as ''auto'',
+	do counters, named strings, quotes, or keyword values such as ''auto'',
 	''nowrap'', or ''baseline''. This is intentional, as the intent of the
 	''attr()'' expression is not to make it possible to describe a
 	presentational language's formatting using CSS, but to enable CSS
@@ -1143,18 +1143,18 @@ <h3 id="attr">
 	value of the ''attr()'' expression is the value of the attribute with that
 	name on the element, according to the rules given below.</p>
 
-	<p>The ''&lt;type>'' argument (which is optional) is a keyword drawn from
+	<p>The optional ''&lt;type>'' argument is a keyword drawn from
 	the list below that tells the UA how to interpret the attribute value.
 	If omitted, ''string'' is implied.  If the type is not valid for where the
 	''attr()'' expression is placed, the whole ''attr()'' expression is invalid.</p>
 
-	<p>The ''&lt;value>'' argument (which is optional) is a CSS value which must
+	<p>The optional ''&lt;value>'' argument is a CSS value which must
 	be valid where the ''attr()'' expression is placed. It represents a fallback
-	value to be used if the named attribute is missing, or its value cannot be
+	value, which is used if the named attribute is missing, or its value cannot be
 	parsed into the	given type or is invalid/out-of-range for the property.  If
 	the ''&lt;value>'' argument is not valid for the property where the ''attr()'' 
 	expression is placed, the whole ''attr()'' expression is invalid.  The 
-	fallback value must not be another ''attr()'' expression; if it is, the
+	fallback value must not contain another ''attr()'' expression; if it is, the
 	outer ''attr()'' expression is invalid.  If the fallback ''&lt;value>'' is 
 	absent, the default value for the given type (from the list below) is implied.</p>
 
@@ -1206,6 +1206,7 @@ <h3 id="attr">
 		used if the property in question only accepts values within a certain
 		range (e.g. positive lengths or angles from 0 to 90deg) and the
 		attribute is out of range (e.g. a negative length or 180deg).
+		If the unit is a relative length, it must be computed to an absolute length.
 
 		<dt>''em''
 		<dt>''ex''
@@ -1230,6 +1231,7 @@ <h3 id="attr">
 		<dd>The attribute value will be interpreted as a CSS ''&lt;number>'', with the given
 		type suffixed as a unit. The default is ''0'' in the relevant
 		units, or else the property's minimum value if ''0'' in the relevant units is not valid for the property.
+		If the unit is a relative length, it must be computed to an absolute length.
 	</dl>
 
 	<div class="example">