[Healeys] Fasteners - Specifications.

[Alan]

Hey gang.
I have an arcane fastener question that I am struggling with.
 
The screws used to retain the aluminium cockpit trim rails are listed as
RPP0312's. The decode of this identifies them as Raised Countersunk screws,
Chrome plated with pointed tips. No.10 thread and 3/4" long.

That's good so far - but what is a No.10 screw thread, or a No.6 (02) for
that matter?
 
Many thanks.........
 _______________________________________________
(______________  Alan Bromfield  _______________)
   (______     \____1957-BN4 ___/    _______)
          (_________________________)
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