ion schema is a type system that can validate ion values and it supports sum types. https://amzn.github.io/ion-schema/docs/spec.html#union https://amzn.github.

ion schema is a type system that can validate ion values and it supports sum types. https://amzn.github.io/ion-schema/docs/spec.html#union https://amzn.github.io/ion-schema/docs/spec.html#union The ion data model doesn't describe a schema or type system. It's a data structure where values are of a known type. In the binary format values are preceded by a type id, in the text format the syntax declares the type - "" for string, {} for struct. The data model doesn't declare what types a value could have, only the type it does have.