Forum OpenACS Q&A: Response to Monitoring dynamic pages viewed when logged in?

Perhaps he's referring to Rob's support to log extendedheaders:
ns_section ns/server/${server}/module/nslog
ns_param   extendedheaders  host
This directive within the config.tcl will direct nslog to log the contents of the host header if it is present.

What you can do is add your own headers to the request headers of a conn within a registered proc or page, and have nslog log those. Something like this:

. . .
ns_set put [ns_conn headers] user_id $user_id
ns_set put [ns_conn headers] shopping_cart_total $shopping_cart_value
. . .
ns_section ns/server/${server}/module/nslog
ns_param   extendedheaders  user_id
ns_param   extendedheaders  shopping_cart_total
Should cause the user_id and shopping_cart_total to be placed into the log for your later analysis.

Along those lines, I patched my nslog module to look for the header X-NO-LOG. If found, it merely returns without logging the request at all. I then have various registered procs and pages add that header at times when I don't want to log a request. I use this to keep various keepalives, robots, and other kinds of entries out of my logs to help keep them a bit more tuned to my needs.