Document urldefrag().
diff --git a/Doc/lib/liburlparse.tex b/Doc/lib/liburlparse.tex
index 8599d20..4819d3c 100644
--- a/Doc/lib/liburlparse.tex
+++ b/Doc/lib/liburlparse.tex
@@ -105,6 +105,13 @@
\code{urlparse()}.
\end{funcdesc}
+\begin{funcdesc}{urldefrag}{url}
+If \var{url} contains a fragment identifier, returns a modified
+version of \var{url} with no fragment identifier, and the fragment
+identifier as a separate string. If there is no fragment identifier
+in \var{url}, returns \var{url} unmodified and an empty string.
+\end{funcdesc}
+
\begin{seealso}
\seerfc{1738}{Uniform Resource Locators (URL)}{