What are the valid data types for API Blueprint?

Question

I am just wondering exactly what the valid data types are when working with API Blueprints?

The documentation seems unclear to me. More specifically, it says:

type is the optional parameter type as expected by the API (e.g. "number", "string", "boolean"). "string" is the default.

Does this mean:

1. Only "number", "string" and "boolean" are valid?
2. It is expecting JSON primitive types?
3. Other?