one of the documented procedures in this installation of the ACS
ad_navbar   args
What it does:
produces navigation bar. notice that navigation bar is different than context bar, which exploits a tree structure. navbar will just display a list of nicely formatted links.
Defined in: /web/philip/packages/acs-core/navigation-procs.tcl

Source code:

    set counter 0
    foreach arg $args {
	lappend link_list "<a href=\"[lindex $arg 0]\">[lindex $arg 1]</a>"
	incr counter
    if { $counter > 0 } {
	return "\[[join $link_list " | "]\]"
    } else {
	return ""