+ # there's actually a very important piece of logic buried in here:
+ # incrementing $late_subtotal{$section} CREATES
+ # $late_subtotal{$section}. keys(%late_subtotal) is later used
+ # to define the list of late sections, and likewise keys(%subtotal).
+ # When _items_cust_bill_pkg is called to generate line items for
+ # real, it will be called with 'section' => $section for each
+ # of these.