The specification type for an APIs.json sets the tone for how the APIs.json will be processed, providing a way to namespace different ways of leveraging the machine-readable contents of the APIs/json. The most common is a simple index of one or many APIs, but originally templates and examples were also allowed. Contracts, blueprints, and a handful of other types have recently been added, expanding the ways in which the APIs.json specification can be used beyond just API discovery. You can find details about the type property for APIs.json.