doubleword(int32), double precision floating-point (float64), integer quadword (int64). Therefore, a ZMM vector register can hold 8, 16, 32, or 64 elements in principle. The length of an opmask register, MAX_KL, is sufficient to handle up to 64 bits. Masking is supported in 64-bit mode. REX prefixes consist of 4-bit fields that form