We are seeing a disturbing trend of libraries removing various 3XX fields from authority records created by NLM to substitute LCSH terms. We would like to remind PCC libraries that not everyone uses LCSH and while it is perfectly permissible to add an additional 3XX from your preferred controlled vocabulary, please do not remove the existing data from authority records.
NLM policy is to always include a 3XX that corresponds to a qualifier in the AAP needed to make it unique or convey the idea that the name is a corporate body. It may or may not come from a controlled vocabulary and that is perfectly acceptable in RDA and the PCC guidelines. For example, several libraries have taken NLM authority records with a 111 we had created with the qualifier (Conference) and deleted our 368 of Conference and substituted a 368 of Congresses and conventions $2 lcsh. We believe the 368 that corresponds to the 111 qualifier needs to remain in the record, with the additional 368 from the controlled vocabulary, if desired.
In a similar type of situation, libraries have changed a 370 field supplied by NLM as a conference location (in correct authorized form) to substitute a more specific location that the library found from further research, but did not appear on the item being cataloged. We ask that PCC libraries respect the judgment of others and add what you need/want to the authority records, but do not remove elements from records that are not incorrect and do not change AAPs unless they are actually wrong.
Head of Cataloging and Metadata Management
National Library of Medicine
8600 Rockville Pike
Bethesda, MD 20894