Provide working definitions for terminology marked as to be defined.

spec/ttml2.xml

@@ -885,12 +885,14 @@ the <loc href="#semantics-procedure-construct-default-processor-profile"><phrase
 procedure.</p>
 </def>
 </gitem>
+<!--
 <gitem id="terms-default-profile">
 <label>[default profile]</label>
 <def>
 <p>&tbd;</p>
 </def>
 </gitem>
+-->
 <gitem id="terms-default-region">
 <label>[default region]</label>
 <def>
@@ -1148,7 +1150,10 @@ a <loc href="#embedded-content-vocabulary-source"><el>source</el></loc> element
 <gitem id="terms-inferred-processor-profile">
 <label>[inferred processor profile]</label>
 <def>
-<p>&tbd;</p>
+<p>A <loc href="#terms-processor-profile">processor profile</loc> determined by the
+<loc href="#semantics-procedure-construct-inferred-processor-profile">construct inferred processor profile</loc> procedure which may
+serve as the <loc href="#terms-effective-processor-profile">effective processor profile</loc> used to perform
+validation processing.</p>
 </def>
 </gitem>
 <gitem id="terms-inline-animation">
@@ -1715,7 +1720,12 @@ and found to be valid as defined by <specref ref="doctypes"/>.</p>
 <gitem id="terms-validating-content-processor">
 <label>[validating content processor]</label>
 <def>
-<p>&tbd;</p>
+  <p>A <loc href="#terms-content-processor">content processor</loc> which performs validation processing on a
+  TTML <loc href="#terms-document-instance">document instance</loc> prior to performing any other type of processing.</p>
+  <note role="elaboration">
+    <p>A validating content processor may have the sole function of validating (or verifying) a document instance,
+    or it may have multiple functions, the first of which is validating (or verifying) a document instance.</p>
+  </note>
 </def>
 </gitem>
 <gitem id="terms-vertical-axis">
@@ -2388,7 +2398,7 @@ processors to avoid processing content that cannot be processed in a manner that
 attribute on the root <el>tt</el> element, (2) one or more <loc href="#profile-vocabulary-profile"><el>ttp:profile</el></loc>
 elements of type <code>processor</code>, or (3) a combination of these two mechanisms.
 If not declared, a processor profile is inferred from a declared content profile or from a
-<loc href="#terms-default-profile">default profile</loc>.</p>
+<loc href="#terms-default-processor-profile">default processor profile</loc>.</p>
 <note role="elaboration">
 <p>It is not a requirement on a conformant <loc href="#terms-document-instance">document instance</loc> that a processor profile be internally
 declared by use of a <loc href="#profile-vocabulary-profile"><el>ttp:profile</el></loc> element or internally referenced by a