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- Primary label may not be a human understandable label. For example, ISNI number is primary label in the ISNI authority.
- Although it is common for primary label to be a single value, some authorities may allow multiple values for the primary label. For example, Wikidata has multiple primary labels for different languages and some may be missing for some languages.
In some authorities, the primary label is critical and in others it may be optional or used for convenience.
- The predicate used to identify primary and variant labels can, and commonly do, differ between authorities.
If DELETE_LABEL is supported, is there a concept of minimally viable data required for a valid entity and would this include a primary label? Thus, when the primary label is removed, does it require a replacement label? What happens for primary label if there is a delete but no add? Probably not a problem because primary label is likely to be minimal required data for a valid record by the authority, so if there is a change, it will always include both the DELETE and ADD.
Discussion on Variant Labels:
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