Thanks napolik for your answer, but I should have specified my acronyms. In this case, MAC stands for Multiple Award Contracts and MATOC stands for Multiple Award Task Order Contracts. I didn't realize that MAC can also stand for Multi-Agency Contracts. From everything that I have read, just about all solicitations and contracts that use MATOC are for construction. And in OMB's Best Practices for Multiple Award Task and Delivery Order Contracting (July 1997), they say MAC=MATOC. There must be some difference.