BS A 311:1997 English Secure PDF English Printed Edition Aerospace. Screws, 100 degrees reduced countersunk head, internal offset cruciform ribbed or unribbed drive, normal shank, short or medium length MJ threads, metallic material, coated or uncoated, strength classes less than or equal to 1100 MPa. Dimensions

standard published 03/15/1997 by British Standards Institution