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<H1 ALIGN="CENTER">Special Purpose Environment Variables</H1>
<P>
Interoperability problems have led to the introduction of
mechanisms to modify the way Apache behaves when talking to particular
clients. To make these mechanisms as flexible as possible, they
are invoked by defining environment variables, typically with
<A HREF="mod/mod_browser.html#browsermatch">BrowserMatch</A>, though
<A HREF="mod/mod_env.html#setenv">SetEnv</A> and
<A HREF="mod/mod_env.html#passenv">PassEnv</A> could also be used, for
example.
</P>
<H2>downgrade-1.0</H2>
<P>
This forces the request to be treated as a HTTP/1.0 request even if it
was in a later dialect.
</P>
<H2>force-no-vary</H2>
<P>
This causes any <CODE>Vary</CODE> fields to be removed from the response
header before it is sent back to the client. Some clients don't
interpret this field correctly (see the
<A HREF="misc/known_client_problems.html">known client problems</A>
page); setting this variable can work around this problem. Setting
this variable also implies <STRONG>force-response-1.0</STRONG>.
</P>
<H2>force-response-1.0</H2>
<P>
This forces an HTTP/1.0 response when set. It was originally implemented as a
result of a problem with AOL's proxies. Some clients may not behave correctly
when given an HTTP/1.1 response, and this can be used to interoperate with
them.
</P>
<H2>nokeepalive</H2>
<P>
This disables <A HREF="mod/core.html#keepalive">KeepAlive</A> when set. Because
of problems with Netscape 2.x and KeepAlive, we recommend the following
directive be used:
</P>
<PRE>
BrowserMatch Mozilla/2 nokeepalive
</PRE>
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