OK On all the flight refuelling stuff I worked on(made in the UK, for fitting to planes in the USA) ), the connectors were lettered as above... and each pin was lettered. It was never left to 'guessing' the right pin, although in this case it seems pretty clear.... Agreed, they're key slots, not lock slots.
TTman wrote in news:qqp6vn$tj3$ snipped-for-privacy@dont-email.me:
It depends on the pin count and how much common sense is involved. Circular arrays are easy. There are types with multiple size and type of pins too. Some only number every tenth pin. I have seen many variants.
Then the slide trays on commercial, yet still mil spec aircraft gear has multi pin, multi guage rectangular connectors with round keys cut half moon that have many orientations and settings to keep the wrong tray from being slid into the wrong slot on an aircraft tray rack.
China has its own aircraft industry, and it's likely that standards are well-maintained in goods that they use internally. No guarantees on exports, though.
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