Polymorphism

Xlang polymorphism preserves a value's concrete registered type when a field, element, or root is declared through a broader type. Every peer must agree on the concrete type identity and compatible field schema.

Runtime rules

Use the selected runtime's schema metadata, registration, and polymorphism pages for exact syntax. The xlang serialization specification defines the shared behavior and limitations.

Do not infer xlang support from host-language inheritance alone. A concrete subtype must have a portable xlang mapping and coordinated registration on every peer that can receive it.