Earlier rules:

Code a (008/10) indicates that the formulation of the 1XX heading conforms to descriptive cataloging rules used prior to the 1967 publication of Anglo-American Cataloguing Rules (AACR 1).

Examples:

08/10   a

100  1#  $aSmith, John,$dAug. 5, 1882-

[Headings established using the A.L.A. Cataloging Rules for Author and Title Entries (1949)]

008/10   a

110  1#  $aBirmingham, Eng.$bKing Edward's School

[Headings established using the A.L.A. Cataloging Rules for Author and Title Entries (1949)]