BS-939 Complete Document History
Engineers' squares (including cylindrical and block squares). Specification

Complete Current Edition:
   2007 EDITION - ENGINEER'S SQUARES (INCLUDING CYLINDRICAL and BLOCK SQUARES), - Oct. 31, 2007

Obsolete Revision Information:
   AMD 4239 - AMENDMENT 1 - April 1, 1983
   1977 EDITION - SPECIFICATION FOR ENGINEER'S - Jan. 1, 1977