control pricing.
You assign a base rate for charging, and it is multiplied by the 'units' ordered. Solves a need where a company wants to offer an ASP style service, that charges per user, at a base cost, but doesn't want a plan for every combination of user amounts.
http://www.sisd.com/cgi-bin/viewcvs.cgi/freeside/httemplate/edit/part_svc.cgi?r1=1.52&r2=1.53 that were lost due to the concurrent service-refactor merge