Change markup of "<stdio.h>" (in the C example) from <sgmltag> to &lt;

and > entities because "stdio.h" is not an SGML tag (a semantical
correction)

en_US.ISO8859-1/books/developers-handbook/secure/chapter.sgml

@@ -158,7 +158,7 @@
       instruction immediately following the function call.  (Inspired
       by <xref linkend="Phrack">)</para>
 
-<programlisting>#include <sgmltag>stdio.h</sgmltag>
+<programlisting>#include &lt;stdio.h&gt;
 
 void manipulate(char *buffer) {
   char newbuffer[80];