one of the documented procedures in this installation of the ACS
ad_redirect_pattern   from_and_to
What it does:
Target of redirects where a URL must be translated from starting with foo to starting with bar
Defined in: /web/philip/tcl/ad-redirect.tcl

Source code:

    set pair [split $from_and_to "|"]
    set from [lindex $pair 0]
    set to [lindex $pair 1]
    set what_the_user_requested [ns_conn url]
    # Added by branimir Jan 26, 2000: URL variables also need to be included:
    if { !([ns_getform] == "") } {
	set url_vars [export_entire_form_as_url_vars]
	append what_the_user_requested ?$url_vars
    ad_returnredirect [ad_string_replace_once $what_the_user_requested $from $to]