BSPP – BRITISH STANDARD PIPE PARALLEL  – Thread form per as 1722.2, ISO 228 (THREAD TYPE), ISO 1179

BSPT – BRITISH STANDARD PIPE TAPER  – Thread form as 1722.1, BS 21, ISO 7-1, DIN 3852-2 FORM C (MALE), DIN 3852-2 FORM Z (FEMALE)