Apache Reference: mod_env

mod_env - Fixed Environment Variable Creation
Since Apache 1.1, src/modules/standard/mod_env.c
Andrew Wilson (1995)

mod_env is a very simple module that performs one basic task: it controls the export of variables to the SSI/CGI environment and allows the webmaster to force values of variables.

Directives:

PassEnv	SetEnv
UnsetEnv