A repository for storing chromatin state definition tables to paint the genome with functional annotation
States are represented by a series of two bit values.
NA - This mark is irrelevant to this state
00 - If this mark is present, it should not overlap with this state
01 - If this mark is present, it should overlap with this state
10 - This mark must be present, and must not overlap with this state
11 - This mark must be present, and must overlap with this state