Apache conf file & variables

How to set up variables in httpd.conf

[ColdFusion]

I was wondering if it is be possible to define a variable in httpd.conf, and then use it in httpd.conf multiple times.

For example define:
XXX = www.MyServer.com

Then use it like this for example:
ErrorDocument 404 [XXX...]
ErrorDocument 405 [XXX...]
ErrorDocument 406 [XXX...]