I was told this several decades ago by someone I trust. I?m waiting for some experts to reply here. In my ex-space industry days, every MS/NAS/AN/etc bolt had the marks on both ends verified at critical installations. All the left overs from that industry have them. Going to check my Spruce purchased ones for consistency. I know the testing standard but can?t tell you how/how often it?s applied. As mentioned, I hope so someone with the correct knowledge chimes in.