$_SERVER['HTTP_ACCEPT_ENCODING'] unavailable

Did anyone experience this? I am working on a script that compresses the output, thus relying on $_SERVER['HTTP_ACCEPT_ENCODING'] to figure out how to encode it. The problem is 'http_accept_encoding' is missing from $_SERVER. I realize the value may not be available all the time, but it seems to be missing regardless of browser / site / etc. Firebug on Firefox shows the http request containing the accept_encoding header being sent to the server and it looks like it gets lost on the way. Is it a config issue in PHP, or in Apache? Can anybody help? Thanks a lot, Vlad My platform is: PHP 5.2.1 + Apache 2.0.58 on Gentoo 2006.0 My $_SERVER looks roughly like this:

    [HTTP_HOST] => lab.vvvlad.com
    [HTTP_USER_AGENT] => Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.4) Gecko/20070515 Firefox/2.0.0.4
    [HTTP_ACCEPT] => text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
    [HTTP_ACCEPT_LANGUAGE] => en-us,en;q=0.5
    [HTTP________________] => ------------
    [HTTP_ACCEPT_CHARSET] => UTF-8,*
    [HTTP_KEEP_ALIVE] => 300
    [HTTP_CONNECTION] => keep-alive
    [HTTP_COOKIE] => tid=b0005b4e81a3dd4d1067884308f4d9fbdc6b169e802298eacdecdb6e9c34aa1a; sid=a55f5a7ea8d512c7115d53fedbcf8375
    [PATH] => /bin:/sbin:/usr/bin:/usr/sbin:/usr/local/sbin:/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/sbin:/bin:/usr/bin:/sbin:/usr/sbin
    [SERVER_SIGNATURE] =>
    [SERVER_SOFTWARE] => Apache
    [SERVER_NAME] => lab.vvvlad.com
    [SERVER_ADDR] => 192.168.2.6
    [SERVER_PORT] => 80
    [DOCUMENT_ROOT] => /srv/hosts/lab.vvvlad.com/htdocs
    [SERVER_ADMIN] => vvvlad@vvvlad.com
    [SCRIPT_FILENAME] => /srv/hosts/lab.vvvlad.com/htdocs/server.php
    [REMOTE_PORT] => 1752
    [GATEWAY_INTERFACE] => CGI/1.1
    [SERVER_PROTOCOL] => HTTP/1.1
    [REQUEST_METHOD] => GET
    [QUERY_STRING] =>
    [REQUEST_URI] => /server.php
    [SCRIPT_NAME] => /server.php
    [PHP_SELF] => /server.php
    [REQUEST_TIME] => 1182044854