Req->vars.auth-user% displays "name of authorized user"

Does this particular functionality support on WS7.0?Req->vars.auth-user% displays "name of authorized user" in accesslog, how to display it also in error log? If support, please advise how to implement.
[226 byte] By [charlenegoha] at [2007-11-27 2:07:07]
# 1
If you run the server in finest level, you will see which user got authenticated. What is the problem you are trying to solve?
mva at 2007-7-12 1:54:54 > top of Java-index,Web & Directory Servers,Web Servers...