074 Subfield $a - GPO item number:
Subfield $a contains the GPO item number. Qualifiers such as MF for microfilm are included in subfield $a.
Examples:
074 ##$a334-C-1
074 ##$a277-A-2 (MF)
074 ##$a1002-A
074 ##$a1002-B (MF)
[Two GPO item numbers associated with one record.]