Consider a specific schema field for unit

[ianfore]

Background
In Search discussion on 2 March the following scope was discussed - see document
What is the scope of Search?

1. agree on how we search for things with a given data model
2. agree on how we describe data models
3. agree on the data models themselves

The conclusion was that 1 and 2 are in scope. 3 is beyond scope for specific models but is facilitated by 2. Notably models defined in 3 would be recorded via 2.

Issue
The issue here concerns 2. The schema provided by /tables//info are how the models in 2 are made available.
The specific request is that the metaschema used for 2 should provide explicit handling of unit of measure in structured form.
The current metaschema is JSON-Schema. In Search examples to date unit have been embedded in $comment.
e.g.

{'age':{
   "type": "number",
   "$comment": "UNIT 'Years'",
   "description": "Participant reference age"
}

Finding some way to include unit should be considered. Likely using an existing semantic standard for unit of measure.
The following is a conceptual illustration of a minimal change to accomplish this.

{'age':{
   "type": "number",
   "unit": "Years",
   "description": "Participant reference age"
}

As a test case, the handling of unit should allow for automated use of the kind of age mappings illustrated in this FASP Script.