The intersection of SETA with SETB replaces SETB.
void lgand(BYTE *seta, long *cpl, BYTE *setb, long *empty)
SETA and SETB are represented as bit-strings of byte-length CPL; i.e. each byte of SETA or SETB represents 8 set members. The presence of a set member is represented by a coresponding on-bit.
CPL may exceed 256 bytes!
EMPTY is set TRUE if the resultant set is empty, and is set FALSE otherwise.