I think the 'X' marking is a bend test proof, not a sold out of service mark:
http://www.radix.net/~bbrown/brit_bayo.html
I think the 'X' marking is a bend test proof, not a sold out of service mark:
http://www.radix.net/~bbrown/brit_bayo.html
Nature and nature's laws lay hid in night;
God said "Let Newton be!" and all was light.