BACK
#define BACK 1003
#define BACK 2
#undef BACK
#define BACK(dst, src, n) ((dst) |= ((unsigned long)(src)&(here)) >> (n))
#undef BACK
#define BACK(dst, src, n) ((dst)[here-(n)] |= (src)[here])
#define BACK 7 /* no Match "", "next" ptr points backward. */
#define BACK 0x406C