Merge pull request #2640 from w3c/fix/whitespace-ref

Switch from infra to xml definition of whitespace for viewport meta

epub33/core/index.html

@@ -11008,11 +11008,33 @@ <h3>Syntax</h3>
 						href="#viewport.ebnf.sep-char">separator characters</a> or the <a href="#viewport.ebnf.assign"
 						>assignment character</a>.</p>
 
+				<div class="proposed correction" id="change_4">
+					<span class="marker">Proposed Correction 4</span>
+					<p data-cite="svg2">The following paragraph mixed in a reference to the [[infra]] specification's
+						definition of whitespace characters, which is only valid for HTML documents. This would have
+						allowed the Form Feed character in <code>viewport meta</code> tags even though Form Feed is not
+						valid XML whitespace character. This change corrects the reference to point to the [[xml]]
+						definition and adds an explanatory note about the difference between the two definitions. For
+						more information, refer to <a href="https://github.com/w3c/epub-specs/issues/2637">issue
+							2637</a>.</p>
+				</div>
+
 				<p>The authoring requirements in this section apply <em>after</em>
 					<a data-cite="xml#AVNormalize">whitespace normalization</a>&#160;[[xml]] (i.e., after a reading
 					system strips leading and trailing whitespace and compacts all instances of multiple whitespace
-					within the attribute to single spaces). EPUB creators MAY include any valid [=ascii whitespace=]
-					[[infra]] in the authored tag so long as the result is valid to this definition.</p>
+					within the attribute to single spaces). EPUB creators MAY include any <ins cite="#change_4"><a
+							data-cite="xml#NT-S">whitespace characters</a> [[xml]]</ins><del cite="#change_4">valid
+						[=ascii whitespace=] [[infra]]</del> in the authored tag so long as the result is valid to this
+					definition.</p>
+
+				<ins cite="#change_4">
+					<div class="note">
+						<p>Although [[html]] <a data-cite="html#dependencies">depends on</a> the [[infra]] <a
+								data-cite="infra#ascii-whitespace">definition of whitespace</a>, the Form Feed (U+000C)
+							character is not valid whitespace per the [[xml]] definition. It cannot be used in the XML
+							syntax (i.e., in XHTML content documents).</p>
+					</div>
+				</ins>
 
 				<p>There are no restrictions on any other attributes allowed on the <a data-cite="html#the-meta-element"
 							><code>meta</code></a> element by the [[html]] grammar.</p>
@@ -12002,12 +12024,15 @@ <h2>Change log</h2>
 				<summary>Substantive changes since the <a href="https://www.w3.org/TR/2023/REC-epub-33-20230525/"
 						>Recommendation</a> of 2023-05-25</summary>
 				<ul>
+					<li>16-July-2024: Fixed the definition of whitespace allowed in viewport meta tags to refer to the
+						characters allowed by the XML standard. See <a
+							href="https://github.com/w3c/epub-specs/issues/2637">issue 2637</a>.</li>
 					<li>25-July-2023: Updated where the <code>epub:type</code> is allowed on SVGs to use the definition
 						of a renderable element. See <a href="https://github.com/w3c/epub-specs/issues/2556">issue
-							2556</a>. </li>
+							2556</a>.</li>
 					<li>25-July-2023: Clarified the definitions of embedded SVGs and moved the restriction on where the
 							<code>epub:type</code> attribute is allowed to apply so it applies to all SVG definitions.
-						See <a href="https://github.com/w3c/epub-specs/issues/2555">issue 2555</a>. </li>
+						See <a href="https://github.com/w3c/epub-specs/issues/2555">issue 2555</a>.</li>
 				</ul>
 			</details>