A data construct is a standardized information layout. The term comes from the phrase 'Constructed Item Unique Identification'. The rules are laid out in MIL-STD-130 and DFARS 252.211-7003. The Department of Defense (DoD) requires its suppliers and their subcontractors to select both a data construct and an encoding format for their UID numbering system. The two most common types of item unique serialization construction layouts approved by the DoD are Construct #1 and Construct #2.