Versions <=v1.0.10 assumed that each affiliation object could have one name (string), one identifier type, and one identifier id. Version 1.0.11 subclasses the affiliation identifier, and each affil object will now have an array of affiliation identifers.
The practical application of this is that if the publisher includes multiple external identifiers for a given author affiliation -- for example an ISNI, ROR, and/or GRID id -- we will be able to store all within the affiliation.