For original cataloging subfields a and c should employ the appropriate NUC codes for Houghton (MH-H) or the Harvard Theatre Collection (MH-HT). However, as the codes get flipped to the OCLC code when taped out, we should not worry about changing current HOLLIS records that are coded HHG.
040 | b eng is also added to records that are taped out, so it is not necessary to enter the subfield b to these records.
For original rare book cataloging employing the DCRM(B) standard, always add an 040 field with subfield e dcrmb:
040 |a MH-H |c MH-H |e dcrmb
For original cataloging employing the RDA standard, always add an 040 field with subfield e rda.
Catalogers may catalog pre-1820 imprints in RDA if they so wish, or use a hybrid RDA/DCRM approach. For more information about hybrid RDA/DCRM records in the current environment, follow this link: PCC RDA BIBCO Standard Record (BSR), April 2014 revision. The subfield e is repeatable and it thus permissible to enter both dcrmb and rda. In general, music catalogers should catalog pre-1830 imprints in DCRM(B) or use a hybrid RDA/DCRM approach
For graphic materials fully cataloged per Elizabeth Betz Parker, Graphic Materials: Rules for Describing Original Items and Historical Collections, add subfield e gihc:
040 |a MH-H |c MH-H |e gihc