Clarifications to handling percentages in calc() due to <http://www.w3.org/mid/4FFB7960.3080700@csail.mit.edu>.

--HG--
extra : rebase_source : c77106c60b7bb17e791a3d576da6fda149446ad3

Author: fantasai

css3-values/Overview.html

@@ -1368,10 +1368,20 @@ <h3 id=calc-notation><span class=secno>8.1. </span> Mathematical
    class=css>calc()</code></a>’ expression is the expression with all
    components computed, with all multiplication/division subexpressions
    resolved, and with all addition/subtraction subexpressions resolved where
-   both sides are the same type. <span class=note> Thus, the computed value
-   of a ‘<a href="#calc"><code class=css>calc()</code></a>’ expression
-   can be represented as either a number or a tuple of a dimension and a
-   percentage. </span>
+   both sides are the same type. Where percentages are not resolved at
+   computed value, they are not resolved in ‘<a href="#calc"><code
+   class=css>calc()</code></a>’ expressions, e.g. ‘<code
+   class=css>height: calc(100% - 100% + 1em)</code>’ computes to ‘<code
+   class=css>height: calc(0% + 1em)</code>’, not to ‘<code
+   class=css>height: calc(1em)</code>’, and, due to containing a percentage
+   relative to the height of a containing block that depends on this
+   element's height, <a
+   href="http://www.w3.org/TR/CSS21/visudet.html#the-height-property">is
+   treated as ‘<code class=css>auto</code>’</a>. <a href="#CSS21"
+   rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a> <span class=note> Thus, the
+   computed value of a ‘<a href="#calc"><code
+   class=css>calc()</code></a>’ expression can be represented as either a
+   number or a tuple of a dimension and a percentage. </span>
    <!-- http://lists.w3.org/Archives/Public/www-style/2010May/0001.html
 	This has notes on how we should handle things when calc() is extended to 
 	handle unit mult/div. Related to this is <unit>mod<unit>, which can return
@@ -1474,12 +1484,12 @@ <h4 id=calc-syntax><span class=secno>8.1.1. </span> Syntax</h4>
 
   <p> UAs must support ‘<a href="#calc"><code
    class=css>calc()</code></a>’ expressions of at least 20 terms, where
-   each ‘<a href="#number"><code class=css>number</code></a>’, ‘<a
-   href="#dimension"><code class=css>dimension</code></a>’, or ‘<a
-   href="#percentage"><code class=css>percentage</code></a>’ is a term. If
-   a ‘<a href="#calc"><code class=css>calc()</code></a>’ expression
-   contains more than the supported number of terms, it must be treated as if
-   it were invalid.
+   each <a href="#number"><code>NUMBER</code></a>, <a
+   href="#dimension"><code>DIMENSION</code></a>, or <a
+   href="#percentage"><code>PERCENTAGE</code></a> is a term. If a ‘<a
+   href="#calc"><code class=css>calc()</code></a>’ expression contains more
+   than the supported number of terms, it must be treated as if it were
+   invalid.
 
   <h4 id=calc-type-checking><span class=secno>8.1.2. </span> Type Checking</h4>
 

css3-values/Overview.src.html

@@ -912,6 +912,12 @@ <h3 id="calc-notation">
 		with all components computed,
 		with all multiplication/division subexpressions resolved,
 		and with all addition/subtraction subexpressions resolved where both sides are the same type.
+		Where percentages are not resolved at computed value,
+		they are not resolved in ''calc()'' expressions,
+		e.g. ''height: calc(100% - 100% + 1em)'' computes to ''height: calc(0% + 1em)'',
+		not to ''height: calc(1em)'',
+		and, due to containing a percentage relative to the height of a containing block that depends on this element's height,
+		<a href="http://www.w3.org/TR/CSS21/visudet.html#the-height-property">is treated as ''auto''</a>. [[!CSS21]]
 		<span class='note'>
 			Thus, the computed value of a ''calc()'' expression can be represented
 			as either a number
@@ -1017,7 +1023,7 @@ <h4 id='calc-syntax'>
 
 	<p>
 		UAs must support ''calc()'' expressions of at least 20 terms, 
-		where each ''number'', ''dimension'', or ''percentage'' is a term.  
+		where each <code>NUMBER</code>, <code>DIMENSION</code>, or <code>PERCENTAGE</code> is a term.  
 		If a ''calc()'' expression contains more than the supported number of terms, 
 		it must be treated as if it were invalid.
 

css3-values/issues-lc-2012.html

@@ -329,3 +329,12 @@ <h1>CSS Values and Units Level 3 Disposition of Comments</h1>
 Response: <a href="http://lists.w3.org/Archives/Public/www-style/2012Jul/0217.html">http://lists.w3.org/Archives/Public/www-style/2012Jul/0217.html</a>
 Closed:   Partially Accepted
 </pre>
+<pre class="a" id="issue-38">
+Issue 38. <a href="#issue-38">#</a>
+Summary:  Clarify whether percentages can be simplified away in calc()
+From:     Kenny Lu
+Comment:  http://www.w3.org/mid/4FFB7960.3080700@csail.mit.edu
+Response: 
+Closed:   Accepted
+</pre>
+

css3-values/issues-lc-2012.txt

@@ -259,3 +259,10 @@ Comment:  http://lists.w3.org/Archives/Public/www-style/2012Jul/0210.html
 Response: http://lists.w3.org/Archives/Public/www-style/2012Jul/0217.html
 Closed:   Partially Accepted
 ----
+Issue 38.
+Summary:  Clarify whether percentages can be simplified away in calc()
+From:     Kenny Lu
+Comment:  http://www.w3.org/mid/4FFB7960.3080700@csail.mit.edu
+Response: 
+Closed:   Accepted
+----