Start documenting precompiled headers
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@72146 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/InternalsManual.html b/docs/InternalsManual.html
index 05b45a6..a4d5a05 100644
--- a/docs/InternalsManual.html
+++ b/docs/InternalsManual.html
@@ -31,7 +31,7 @@
<ul>
</ul>
</li>
-<li><a href="#pth">Pretokenized Headers (PTH)</a>
+<li><a href="#pch">Precompiled Headers</a>
<li><a href="#libfrontend">The Frontend Library</a>
<ul>
</ul>
@@ -548,11 +548,19 @@
href="DriverInternals.html">here<a>.<p>
<!-- ======================================================================= -->
-<h2 id="pth">Pretokenized Headers (PTH)</h2>
+<h2 id="pch">Precompiled Headers</h2>
<!-- ======================================================================= -->
-<p>Clang's current implementation of precompiled headers, known as PTH, is
-documented <a href="PTHInternals.html">here</a>.</p>
+<p>Clang supports two implementations of precompiled headers. The
+ default implementation, precompiled headers (<a
+ href="PCHInternals.html">PCH</a>) uses a serialized representation
+ of Clang's internal data structures, encoded with the <a
+ href="http://llvm.org/docs/BitCodeFormat.html">LLVM bitstream
+ format</a>. Pretokenized headers (<a
+ href="PTHInternals.html">PTH</a>), on the other hand, contain a
+ serialized representation of the tokens encountered when
+ preprocessing a header (and anything that header includes).</p>
+
<!-- ======================================================================= -->
<h2 id="libfrontend">The Frontend Library</h2>