[users@httpd] What EnvVars are available?

[SixArm]

I'm trying to add server reply headers to describe the connection to Apache for tesing purposes.

This is on Apache/2.0.52 on RedHat EL3. 

<VirtualHost $ip_alias:$web_server_port>
    DocumentRoot /doc_root
    PassEnv SERVER_ADDR
    PassEnv SERVER_PORT
    PassEnv REMOTE_ADDR
    PassEnv REMOTE_PORT
    PassEnv PATH
    Header set SERVER_ADDR %{SERVER_ADDR}e
    Header set SERVER_PORT %{SERVER_PORT}e
    Header set REMOTE_ADDR %{REMOTE_ADDR}e
    Header set REMOTE_PORT %{REMOTE_PORT}e
    Header set PATH %{PATH}e
</VirtualHost>


The Env Vars are not defined but I can insert a header for PATH.  I can view all these variable in a simple phpinnfo() call.  I've also written an Apache 1.3 module which accomplishes the same thing.  I was hoping I could accomplish without an additional module or php.

Can anyone explain why these variable are not available?  Or how I can see what variables are available.  From what I've read in the Apache docs they should be available.

Thanks for any help,

-Sixarm