1. A method, in a data processing system, for converting a set of single-layer design rules into a set of split-layer design rules for double patterning lithography (DPL), the method comprising: identifying, by a processor in the data processing system, the set of single-layer design rules and minimum lithographic resolution pitch constraints for single exposure, wherein the set of single-layer design rules comprise a first plurality of minimum distances that are required by a set of first shapes in a single-layer design; modifying, by the processor, each of the first plurality of minimum distances in the set of single-layer design rules with regard to the minimum lithographic resolution pitch constraints for single exposure, thereby forming the set of split-layer design rules, wherein the set of split-layer design rules comprise at least a second plurality of minimum distances that are required by at least a set of second shapes and a set of third shapes in a split-layer design; and coding, by the processor, the set of split-layer design rules into a design rule checker for use in designing a double patterning lithography design.