diff --git a/docs/UsersManual.html b/docs/UsersManual.html
index 7d7f263..4ba00e0 100644
--- a/docs/UsersManual.html
+++ b/docs/UsersManual.html
@@ -286,6 +286,30 @@
 diagnostic, either from the command line or through <a 
 href="#pragma_GCC_diagnostic">#pragma GCC diagnostic</a>.</dd>
 
+<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
+<dt id="opt_fdiagnostics-show-category"><b>-fdiagnostics-show-category=none/id/name</b>:
+Enable printing category information in diagnostic line.</dt>
+<dd>This option, which defaults to "none",
+controls whether or not Clang prints the category associated with a diagnostic
+when emitting it.  Each diagnostic may or many not have an associated category,
+if it has one, it is listed in the diagnostic categorization field of the
+diagnostic line (in the []'s).</p>
+
+<p>For example, a format string warning will produce these three renditions
+based on the setting of this option:</p>
+
+<pre>
+  t.c:3:11: warning: conversion specifies type 'char *' but the argument has type 'int' [-Wformat]
+  t.c:3:11: warning: conversion specifies type 'char *' but the argument has type 'int' [-Wformat<b>,1</b>]
+  t.c:3:11: warning: conversion specifies type 'char *' but the argument has type 'int' [-Wformat<b>,Format String</b>]
+</pre>
+
+<p>This category can be used by clients that want to group diagnostics by
+category, so it should be a high level category.  We want dozens of these, not
+hundreds or thousands of them.</p>
+</dd>
+
+
 
 <!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
 <dt id="opt_fdiagnostics-fixit-info"><b>-f[no-]diagnostics-fixit-info</b>:
@@ -393,6 +417,10 @@
 <li>An option that indicates how to control the diagnostic (for diagnostics that
     support it) [<a 
    href="#opt_fdiagnostics-show-option">-fdiagnostics-show-option</a>].</li>
+<li>A high-level category for the diagnostic for clients that want to group
+    diagnostics by class (for diagnostics that
+    support it) [<a 
+   href="#opt_fdiagnostics-show-category">-fdiagnostics-show-category</a>].</li>
 <li>The line of source code that the issue occurs on, along with a caret and
     ranges that indicate the important locations [<a
     href="opt_fcaret-diagnostics">-fcaret-diagnostics</a>].</li>