Non-ISBD:

Code # (blank ) in Leader/18 indicates that the record is not formulated according to International Standard Bibliographic Description (ISBD) conventions. Records do not follow the descriptive cataloging and punctuation practices of the ISBD in the descriptive portion of the record.

Examples of cataloging rules that do not follow ISBD conventions are: Catalog Rules, Author and Title Entries (1908); A.L.A. Catalog Rules, Author and Title Entries (1941); A.L.A. Cataloging Rules for Author and Title Entries (1949); and Anglo-American Cataloguing Rules, 1st Edition (AACR 1) (except the revised chapters). The Anglo-American Cataloguing Rules (second edition) are based on the ISBD general framework for the description of library materials, including the order of elements in the catalog entry and prescribed punctuation.