The is the gold standard for reference because:
The top-left corner identifies the rivet part number, typically using AN (Army-Navy) or MS (Military Standard) designations. "BJ" might identify a standard MS20470AD rivet. nas523 pdf top
A: Largely, yes. NAS523 is the aerospace adoption of Z1.4. However, the "top" difference is that NAS523 includes specific notes regarding fastener traceability and critical defect management that Z1.4 does not cover. If your contract calls out NAS523, do NOT substitute Z1.4. The is the gold standard for reference because: