+NAME="FILTER-CLIENT-HEADERS"
+></A
+>8.5.13. filter-client-headers</H4
+><P
+></P
+><DIV
+CLASS="VARIABLELIST"
+><DL
+><DT
+>Typical use:</DT
+><DD
+><P
+> To apply filtering to the client's (browser's) headers
+ </P
+></DD
+><DT
+>Effect:</DT
+><DD
+><P
+>Extend filtering capabilities to the client's headers, which
+ by default applies only to the document itself.
+ </P
+></DD
+><DT
+>Type:</DT
+><DD
+><P
+>Boolean.</P
+></DD
+><DT
+>Parameter:</DT
+><DD
+><P
+> N/A
+ </P
+></DD
+><DT
+>Notes:</DT
+><DD
+><P
+> Regular expressions can be used to filter headers as well. Check your
+ filters closely before activating this action, as it can easily lead to broken
+ requests.
+ </P
+><P
+>
+ These filters are applied to each header on its own, not to them
+ all at once. This makes it easier to diagnose problems, but on the downside
+ you can't write filters that only change header x if header y's value is
+ z.
+ </P
+><P
+> The filters are used after the other header actions have finished and can
+ use their output as input.
+ </P
+><P
+> Whenever possible one should specify <TT
+CLASS="LITERAL"
+>^</TT
+>,
+ <TT
+CLASS="LITERAL"
+>$</TT
+>, the whole header name and the colon, to make sure
+ the filter doesn't cause havoc to other headers or the
+ page itself. For example if you want to transform
+ <SPAN
+CLASS="APPLICATION"
+>Galeon</SPAN
+> User-Agents to
+ <SPAN
+CLASS="APPLICATION"
+>Firefox</SPAN
+> User-Agents you
+ shouldn't use:</P
+><P
+><TABLE
+BORDER="0"
+BGCOLOR="#E0E0E0"
+WIDTH="90%"
+><TR
+><TD
+><PRE
+CLASS="SCREEN"
+>s@Galeon/\d\.\d\.\d @@</PRE
+></TD
+></TR
+></TABLE
+></P
+><P
+> but:</P
+><P
+><TABLE
+BORDER="0"
+BGCOLOR="#E0E0E0"
+WIDTH="90%"
+><TR
+><TD
+><PRE
+CLASS="SCREEN"
+>s@^(User-Agent:.*) Galeon/\d\.\d\.\d (Firefox/\d\.\d\.\d\.\d)$@$1 $2@</PRE
+></TD
+></TR
+></TABLE
+></P
+></DD
+><DT
+>Example usage (section):</DT
+><DD
+><P
+> <TABLE
+BORDER="0"
+BGCOLOR="#E0E0E0"
+WIDTH="90%"
+><TR
+><TD
+><PRE
+CLASS="SCREEN"
+>{+filter-client-headers +filter{test_filter}}
+problem-host.example.com
+ </PRE
+></TD
+></TR
+></TABLE
+>
+ </P
+></DD
+></DL
+></DIV
+></DIV
+><DIV
+CLASS="SECT3"
+><H4
+CLASS="SECT3"
+><A
+NAME="FILTER-SERVER-HEADERS"
+></A
+>8.5.14. filter-server-headers</H4
+><P
+></P
+><DIV
+CLASS="VARIABLELIST"
+><DL
+><DT
+>Typical use:</DT
+><DD
+><P
+> To apply filtering to the server's headers
+ </P
+></DD
+><DT
+>Effect:</DT
+><DD
+><P
+>Extend filtering capabilities to the server's headers, which
+ by default applies only to the document itself.
+ </P
+></DD
+><DT
+>Type:</DT
+><DD
+><P
+>Boolean.</P
+></DD
+><DT
+>Parameter:</DT
+><DD
+><P
+> N/A
+ </P
+></DD
+><DT
+>Notes:</DT
+><DD
+><P
+> Similar to <TT
+CLASS="LITERAL"
+>filter-client-headers</TT
+>, but works on
+ the server instead. To filter both server and client, use both.
+ </P
+><P
+> As with <TT
+CLASS="LITERAL"
+>filter-client-headers</TT
+>, check your
+ filters before activating this action, as it can easily lead to broken
+ requests.
+ </P
+><P
+>
+ These filters are applied to each header on its own, not to them
+ all at once. This makes it easier to diagnose problems, but on the downside
+ you can't write filters that only change header x if header y's value is
+ z.
+ </P
+><P
+> The filters are used after the other header actions have finished and can
+ use their output as input.
+ </P
+><P
+> Remember too, whenever possible one should specify <TT
+CLASS="LITERAL"
+>^</TT
+>,
+ <TT
+CLASS="LITERAL"
+>$</TT
+>, the whole header name and the colon, to make sure
+ the filter doesn't cause havoc to other headers or the
+ page itself. See above for example.
+ </P
+></DD
+><DT
+>Example usage (section):</DT
+><DD
+><P
+> <TABLE
+BORDER="0"
+BGCOLOR="#E0E0E0"
+WIDTH="90%"
+><TR
+><TD
+><PRE
+CLASS="SCREEN"
+>{+filter-server-headers +filter{test_filter}}
+problem-host.example.com
+ </PRE
+></TD
+></TR
+></TABLE
+>
+ </P
+></DD
+></DL
+></DIV
+></DIV
+><DIV
+CLASS="SECT3"
+><H4
+CLASS="SECT3"
+><A