Why does eduPerson include the eduPersonOrcid attribute and not eduPersonResearcherId? Won't this lead to new attributes for every kind of identifier?
Yes, it will, very deliberately. Combining multiple types of data into a single attribute precludes use cases in which only a subset of that data may be relevant, unless the data is encoded in a way that allows the different types of data to be recovered. That in turn adds extra work to a consumer of the data.
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