The '/23' indicates a specific detail specification sheet under MIL-DTL-24308, which for this part number identifies a high-density receptacle with female sockets. The '63' combined with '/23' specifies a 44-position insert arrangement. The 'F' suffix denotes Cadmium shell plating. M24308 is a United States military standard (MIL-DTL-24308) for D-subminiature connectors, specifying requirements for nonenvironmental, polarized shell, miniature, rack and panel connectors.