standards-track RFC
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... top-level type can be
defined to accommodate it. Such a definition MUST be done via
standards-track RFC; no other mechanism can be used to define
additional top-level content types ...
... media types MUST have properly formed type and subtype names.
All type names MUST be defined by a standards-track RFC. All
type/subtype name pairs MUST be unique and MUST contain the proper
...