Should data types include 'enum' for restricted value sets?

[jaeddy]

Current data types listed in the docs include:

• Simple Data Types
  • string
  • url
  • code
  • identifier
  • class
  • date
  • dateTime
  • duration
• Complex Data Types
  • Coding

Thinking about JSON Schema / OpenAPI types, are there any cases in which the allowed values would be constrained to a specific set of strings?