CD.COM.01 identifier_type

An identifier type includes unique numbers legally assigned to individuals.

Reference: Types of ID

Code	Values
UIN	Unique identification number
BRN	Birth registration number or birth serial number
MRN	Marriage registration number
DRN	Death registration number

JSON-LD File on GitHub

https://schema.spdci.org/core/v1/code/IdentifierTypeEnum.jsonldschema.spdci.org