[css-display-3] Clarify that 'display' has no effect on semantics. w3c#2355

Author: fantasai

css-display-3/Overview.bs

@@ -126,7 +126,7 @@ Introduction</h2>
 	Note: Further information on the “aural” box tree
 	and its interaction with the 'display' property
 	can be found in the <a href="https://www.w3.org/TR/css3-speech/#aural-model">CSS Speech Module</a>.
-	[[!CSS3-SPEECH]]
+	[[!CSS-SPEECH-1]]
 
 <h3 id="placement">
 Module interactions</h3>
@@ -177,6 +177,17 @@ Box Layout Modes: the 'display' property</h2>
 	such as ''list-item'', which also generates a ''::marker'' pseudo-element,
 	and ''display/none'', which causes the element's entire subtree to be left out of the box tree.
 
+	<div class="advisement">
+		The 'display' property has no effect on an element’s semantics:
+		these are defined by the <a>document language</a> and <em>are not affected by CSS</em>.
+		Aside from the ''display/none'' value,
+		which also affects aural/speech output [[!CSS-SPEECH-1]],
+		the 'display' property only affects visual layout:
+		its purpose is to allow designers freedom
+		to change the layout behavior of an element
+		<em>without</em> affecting the underlying document semantics.
+	</div>
+
 	Values are defined as follows:
 
 	<pre class='prod'>