one of the documented procedures in this installation of the ACS
sub_page_validation   args
What it does:
Use this inside a page_validation block which needs to check more than one thing. Put this around each part that might signal an error.
Defined in: /web/philip/packages/acs-core/utilities-procs.tcl

Source code:

    # to allow this to be at any level, we search up the stack for {%%exception_list}
    set depth [info level]
    for {set level 1} {$level <= $depth} {incr level} {
	upvar $level {%%exception_list} {%%exception_list}
	if { [info exists {%%exception_list}] } {
    if { ![info exists {%%exception_list}] } {
	error "sub_page_validation not inside page_validation"
    foreach validation_block $args {
	if { [catch {uplevel $validation_block} errmsg] } {
	    lappend {%%exception_list} $errmsg