one of the documented procedures in this installation of the ACS
ec_product_file_directory   product_id
What it does:
Returns the directory that that the product files are located under the ecommerce product data directory. This is the two lowest order digits of the product_id.
Defined in: /web/philip/tcl/ecommerce-utilities.tcl

Source code:

    set id_length [string length $product_id]

    if { $id_length == 1 } {
	# zero pad the product_id
	return "0$product_id"
    } else {
	# return the lowest two digits
	return [string range $product_id [expr $id_length - 2] [expr $id_length - 1]]