one of the documented procedures in this installation of the ACS
util_httpopen   method   url   { rqset "" }   { timeout "30" }   { http_referer "" }
What it does:
Like ns_httpopen but works for POST as well; called by util_httppost
Defined in: /web/philip/packages/acs-core/utilities-procs.tcl

Source code:

	if ![string match http://* $url] {
		return -code error "Invalid url \"$url\":  _httpopen only supports HTTP"
	set url [split $url /]
	set hp [split [lindex $url 2] :]
	set host [lindex $hp 0]
	set port [lindex $hp 1]
	if [string match $port ""] {set port 80}
	set uri /[join [lrange $url 3 end] /]
	set fds [ns_sockopen -nonblock $host $port]
	set rfd [lindex $fds 0]
	set wfd [lindex $fds 1]
	if [catch {
		_ns_http_puts $timeout $wfd "$method $uri HTTP/1.0\r"
		if {$rqset != ""} {
			for {set i 0} {$i < [ns_set size $rqset]} {incr i} {
				_ns_http_puts $timeout $wfd  "[ns_set key $rqset $i]: [ns_set value $rqset $i]\r"
		} else {
			_ns_http_puts $timeout $wfd  "Accept: */*\r"

		    	_ns_http_puts $timeout $wfd "User-Agent: Mozilla/1.01 \[en\] (Win95; I)\r"    
		    	_ns_http_puts $timeout $wfd "Referer: $http_referer \r"    

    } errMsg] {
		global errorInfo
		#close $wfd
		#close $rfd
		if [info exists rpset] {ns_set free $rpset}
		return -1
	return [list $rfd $wfd ""]