Definition of a Top-Level Media Type

The definition of a top-level media type consists of:

1. a name and a description of the type, including criteria for whether a particular type would qualify under that type,
2. the names and definitions of parameters, if any, which are defined for all subtypes of that type (including whether such parameters are required or optional),
3. how a user agent and/or gateway should handle unknown subtypes of this type,
4. general considerations on gatewaying entities of this top-level type, if any, and
5. any restrictions on content-transfer-encodings for entities of this top-level type.