EIDR, ISAN, and other authority records

[cjcodeproj]

The catalog element should contain a structure that can handle and reference identity metadata numbers, like ISAN (International Standard Audiovisual Number) or EIDR (Entertainment Identifier Registry).

The element structure should be able to handle appropriate values, it should use a regular expression to validate the values are correct, and there should be hyperlinks or XLinks support if there are external records out there.

If possible, the element name should reflect the content, so it's easy to discover using an XPath query.

Reference Informational Links

EIDR https://www.eidr.org/

ISAN https://www.isan.org