From b4d6a22a1d652dd71f029628b42043d4762c384d Mon Sep 17 00:00:00 2001
From: Pierre-Anthony Lemieux <pal@sandflow.com>
Date: Tue, 17 Jul 2018 07:43:22 -0700
Subject: [PATCH] Clarify that the concrete encoding uses XML 1.0 (#431)

Recommend against use of entity expansion (#431)
---
 imsc1/spec/ttml-ww-profiles.html | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/imsc1/spec/ttml-ww-profiles.html b/imsc1/spec/ttml-ww-profiles.html
index a851dbb7..3e1683d6 100644
--- a/imsc1/spec/ttml-ww-profiles.html
+++ b/imsc1/spec/ttml-ww-profiles.html
@@ -2051,7 +2051,21 @@ <h2>Common Provisions</h2>
     <section>
       <h3>Document Encoding</h3>
 
-      <p>A <a>Document Instance</a> SHALL use UTF-8 character encoding as specified in [[!UNICODE]].</p>
+      <p>A <a>Document Instance</a> SHALL be concretely encoded as a well-formed XML 1.0 [[!xml-20081126]] document using the UTF-8
+      character encoding as specified in [[!UNICODE]].</p>
+
+      <p>The resulting [[!xml-20081126]] document SHOULD NOT contain any of the following physical structures:</p>
+
+      <ul>
+        <li><em>entity declarations</em>; and</li>
+
+        <li><em>entity references</em> other than to <em>predefined entities</em>.</li>
+      </ul>
+
+      <p class="note">These physical structures are intended to be prohibited in future versions of this specification.</p>
+
+      <p class="note">The resulting [[!xml-20081126]] document can contain <em>character references</em>, and <em>entity references</em>
+      to <em>predefined entities</em>.</p>
     </section>
 
     <section id='foreign-elements'>