Support for `reference`-as-a-set

[blelump]

Problem overview

Thinking of a data model where a reference in an object can be any of or one of the values in the set that defines the finite options is quite a common problem. Let's just consider a vehicle that can be a car, bicycle or truck. We then have { car, bicycle, truck } values in a set.

Constraining to a set of values for an attribute of type Reference is currently not supported. What's the DSWG view on this topic?

It is worth noting JSON Schema comes with a composition model that already proposes usage any of or one of concepts. Yet, it has a broader meaning because it also enables the composition of schemas out of subschemas. What's the DSWG view also on this topic?

[carlyh-micb]

ADC has considered this to be covered by setting the attribute type to be an array, and using the cardinality overlay to specify number of accepted values. This applies to any data array type. The options may or may not be specified in a specific set of entry codes.