one of the documented procedures in this installation of the ACS
ec_category_subcategory_and_subsubcategory_display   db   category_list   subcategory_list   subsubcategory_list
What it does:
Returns an HTML table of category, subcategory, and subsubcategory information
Defined in: /web/philip/tcl/ecommerce-defs.tcl

Source code:

    if { [empty_string_p $category_list] } {
	return "None Defined"

    set to_return "<table border=0 cellspacing=0 cellpadding=0>\n"
    foreach category_id $category_list {
	append to_return "<tr>\n"
	set tr_done 1

	if { ![empty_string_p $subcategory_list] } {
	    set relevant_subcategory_list [database_to_tcl_list $db "select subcategory_id from ec_subcategories where category_id=$category_id and subcategory_id in ([join $subcategory_list ","]) order by subcategory_name"]
	} else {
	    set relevant_subcategory_list [list]

	if { [llength $relevant_subcategory_list] == 0 } {
	    append to_return "<td valign=top>[ec_space_to_nbsp [database_to_tcl_string $db "select category_name from ec_categories where category_id=$category_id"]]</td><td></td><td></td>\n"
	} else {
	    append to_return "<td valign=top rowspan=[llength $relevant_subcategory_list]>[ec_space_to_nbsp [database_to_tcl_string $db "select category_name from ec_categories where category_id=$category_id"]]</td>"

	    foreach subcategory_id $relevant_subcategory_list {

		if { $tr_done } {
		    set tr_done 0
		} else {
		    append to_return "<tr>\n"

		append to_return "<td valign=top>&nbsp;--&nbsp;[ec_space_to_nbsp [database_to_tcl_string $db "select subcategory_name from ec_subcategories where subcategory_id=$subcategory_id"]]</td><td valign=top>"

		if { ![empty_string_p $subsubcategory_list] } {
		    set relevant_subsubcategory_name_list [database_to_tcl_list $db "select subsubcategory_name from ec_subsubcategories where subcategory_id=$subcategory_id and subsubcategory_id in ([join $subsubcategory_list ","]) order by subsubcategory_name"]
		} else {
		    set relevant_subsubcategory_name_list [list]
		foreach subsubcategory_name $relevant_subsubcategory_name_list {
		    append to_return "&nbsp;--&nbsp;[ec_space_to_nbsp $subsubcategory_name]<br>\n"

		append to_return "</td></tr>"

	    } ; # end foreach subcategory_id

	} ; # end of case where relevant_subcategory_list is non-empty

    } ; # end foreach category_id
    append to_return "</table>\n"
    return $to_return