diff --git a/spec/ttml2.xml b/spec/ttml2.xml
index 03593dd37..48f06c794 100644
--- a/spec/ttml2.xml
+++ b/spec/ttml2.xml
@@ -9678,6 +9678,11 @@ as determined above effectively becomes the value of <att>tts:direction</att> in
 <p>In the case of any other element <emph><code>E</code></emph>, where <emph><code>E</code></emph> is not a
 <loc href="#layout-vocabulary-region"><el>region</el></loc> element, the presence or absence of a <att>tts:writingMode</att> attribute
 has no affect on the resolution of the computed value of <att>tts:direction</att> on <emph><code>E</code></emph>.</p>
+<note role="clarification">
+<p>The semantics described above correspond to the <emph>XSL modifications to the CSS definition</emph> of the
+<code>direction</code> property as defined by <bibref ref="xslfo11"/> &sect;7.29.1, and, as such, are included in the scope of the
+<loc href="#feature-direction"><code>#direction</code></loc> feature.</p>
+</note>
 </div4>
 </div3>
 <div3 id="style-attribute-disparity">