This British Standard comprises three sections:

Section 1, which specifies limits of size for tapped holes to accommodate wire thread inserts to provide thread sizes from ¼ in to 1½ in UNC inclusive and from ½ in to1in UNF inclusive;

Section 2, which recommends screwing taps intended to produce holes to the limits of size specified in Section 1;

Section 3, which gives a recommended gauging system for checking the tapped holes.