Relates to measuring cylinders for ISO metric threads given in BS 3643. Appendix covers cylinders for use with Unified, Whitworth form and BA threads.Cross References:BS 84BS 93BS 427:Part 1BS 1580:Parts 1 & 2BS 1580:Part 3BS 3643:Part 1BS 3643:Part 2Replaces BS 3777:1964 which remains current.