1. An article of manufacture encoded with at least two integrated circuit (IC) designs, and setup information, the article of manufacture including a computer-readable medium holding data comprising: a first IC design comprising a plurality of first instances of combinational cells, a plurality of second instances of sequential cells, and a plurality of first nets interconnecting the first instances and the second instances, wherein each first instance in the plurality of first instances is instantiated from a cell library A; and a second IC design comprising a plurality of third instances of combinational cells, a plurality of fourth instances of sequential cells, and a plurality of second nets interconnecting the third instances and the fourth instances, wherein each third instance in the plurality of third instances is instantiated from a cell library B; and a logical relationship relating at least one of the second instances to at least one of the fourth instances, the logical relationship further comprising a direction selected to be one of (forward and backward).