20. The search engine of claim 19 , wherein: the bitmap is stored in a compressed format.
19. The search engine of claim 18 , wherein: the bitcheck command contains a bitmap including a plurality of compliance bits, each indicating whether a corresponding reference character of a general set of characters is a member of the specified set of characters; and the first co-processor references each of the input characters to a corresponding compliance bit in the bitmap to generate the compliance signal.