Merge pull request #1724 from w3c/fix/issue-1687

Add note about the problem accessing resources

epub33/core/index.html

@@ -5229,6 +5229,15 @@ <h4>File and Directory Structure</h4>
 						descendant from the Root Directory, provided they are not within the <code>META-INF</code>
 						directory. EPUB Creators MUST NOT reference files in the <code>META-INF</code> directory from an
 						EPUB Publication.</p>
+
+					<div class="note">
+						<p>Some Reading Systems do not provide access to resources outside the directory where the
+							Package Document is stored. EPUB Creators should therefore place all resources at or below
+							the directory containing the Package Document to avoid interoperability issues.</p>
+						<p>This problem is more commonly encountered when <a
+								href="https://www.w3.org/TR/epub-multi-rend-11/#container">creating multiple
+								renditions</a> [[EPUB-MULTI-REND]] of the publication.</p>
+					</div>
 				</section>
 
 				<section id="sec-container-iri">
@@ -9350,8 +9359,11 @@ <h3>Substantive Changes since the <a href="https://www.w3.org/TR/2021/WD-epub-33
 				-->
 
 				<ul>
-					<li> 23-June-2021: Added the <code>base</code> element to the list of discouraged XHTML constructs.
-						See <a href="https://github.com/w3c/epub-specs/issues/1699">issue 1699</a>. </li>
+					<li>28-June-2021: Added a note discouraging EPUB Creators from referencing resources outside the
+						directory containing the Package Document to avoid interoperability issues. See <a
+							href="https://github.com/w3c/epub-specs/issues/1687">issue 1687</a></li>
+					<li>23-June-2021: Added the <code>base</code> element to the list of discouraged XHTML constructs.
+						See <a href="https://github.com/w3c/epub-specs/issues/1699">issue 1699</a>.</li>
 					<li>18-June-2021: Moved requirements for authoring SSML, PLS lexicons and CSS 3 Speech to the <a
 							href="https://www.w3.org/TR/epub-3-tts">EPUB 3 Text-to-Speech Enhancements</a> note. The
 						ability to use these technologies in EPUB 3 Publications remains unchanged. See <a

epub33/multi-rend/index.html

@@ -263,13 +263,35 @@ <h2>Specifying Multiple Renditions</h2>
 				Publication Resources.</p>
 
 			<div class="note">
-				<p>If the Package Documents for each Rendition are stored in separate directories, as shown in the <a
-						href="#sep-dir">preceding example</a>, Reading Systems may prevent one Rendition from accessing
-					the resources of another (i.e., to prevent publications from trying to reach outside the EPUB
-					Container, referencing the parent directory or above of a Package Document may be forbidden).</p>
+				<p>Renditions may not be able to access resources stored in sibling directories on all Reading Systems
+					(i.e., some Reading Systems do not provide access outside the directory a Rendition's Package
+					Document is stored in).</p>
+
+				<p>For example, given the following directory structure (all resources except the Package Documents
+					omitted for clarity):</p>
+
+				<pre>/META-INF
+/Rendition1
+   - rendition1.opf
+/Rendition2
+   - rendition2.opf
+/Shared</pre>
+
+				<p>Resources in the "<code>Rendition1</code>" directory may not be able to access resources in either
+						"<code>Rendition2</code>" or "<code>Shared</code>".</p>
 
 				<p>To share resources between Renditions, it is recommended that the Package Documents be located in a
 					common directory and the resources for each Rendition stored in separate subdirectories.</p>
+
+				<p>Restructuring the previous example as follows would allow shared access to all resources:</p>
+
+				<pre class="prettyprint">/META-INF
+/EPUB
+   /Rendition1
+   /Rendition2
+   /Shared
+   - rendition1.opf
+   - rendition2.opf</pre>
 			</div>
 		</section>
 		<section id="sec-metadata">