one of the documented procedures in this installation of the ACS
ad_dimensional_set_variables   option_list   { options_set "" }
What it does:
set the variables defined in option_list from the form provided (form defaults to ns_conn form) or to default value from option_list if not in the form data.

You only really need to call this if you need the variables (for example to pick which select statement and table to actually use)

Defined in: /web/philip/packages/acs-core/table-display-procs.tcl

Source code:

    set out {}

    if {[empty_string_p $option_list]} {

    if {[empty_string_p $options_set]} {
        set options_set [ns_getform]

    foreach option $option_list { 
        # find out what the current option value is.
        # check if a default is set otherwise the first value is used
        set option_key [lindex $option 0]
        set option_val {}
        # get the option from the form
        if { ! [empty_string_p $options_set] && [ns_set find $options_set $option_key] != -1} {
            uplevel [list set $option_key [ns_set get $options_set $option_key]]
        } else {
            uplevel [list set $option_key [lindex $option 2]]