Vatican Rules - british museum cataloguing rules:

Vatican Library. Rules for the Catalogue of Printed Books I translated from the 2nd Italian edition 1938, by the very Rev. Thomas J. Shanahan, Victor A. Shaefer, Constantine T. Vesselowsky; Wyllis E. Wright, editor. -- Chicago: American Library Association, 1948. - 3rd Italian edition published in 1949. 

The code was the result of a decision taken in 1927 to prepare a new catalogue of the printed books in the Vatican Library (Rome) which was in the process of reorganisation. Since the catalogue of the Original collection prepared at the end of the 17th century was incomplete and also outmoded, a new up-to-date catalogue was contemplated. 

Because of the involvement of the American experts and of American trained personnel, the code reflected American bias. Wyllis E. Wright, who wrote the foreword to the English translation of the code claimed it as "the most complete statement of American cataloguing practice." 

Next to Cutter's rules, this was the other code that was a complete and comprehensive code, covering all the aspects of cataloguing. It provided for entry (author, title entries), description, subject headings and filing. The rules for subject cataloguing stated general principles and included instructions on forms and specific areas of application. It is also claimed as an international code.