Media Type Registration

Media Type Registration is the process for adding a new internet media type (formerly MIME type) to the IANA registry, defined by RFC 6838, which obsoleted the older RFC 2048. The goal is to keep the `type/subtype` namespace coordinated across email, HTTP, and other protocols while allowing software vendors to mint identifiers for their own formats without IETF involvement. RFC 6838 partitions the namespace into four trees. The standards tree (no prefix, e.g. `image/png`) is reserved for types tied to recognized standards organizations and normally requires an IETF specification or formal expert review. The vendor tree (`vnd.` prefix, e.g. `application/vnd.ms-excel`) lets companies and consortia register identifiers for publicly available products with light review. The personal tree (`prs.` prefix) covers experimental or non-commercial uses. The unregistered tree (`x.` prefix) is private; identifiers there cannot be added to the registry and risk collision. The submission flow is mostly email-driven: applicants post a registration template to the `media-types@iana.org` list and to IANA, including the proposed identifier, encoding considerations, security considerations, intended usage, and contact information. Designated experts review for namespace collisions, well-formed syntax, and a real use case. A provisional registration mechanism allows standards-tree names to be reserved early, before the underlying specification is finished. RFC 6838 also defines structured suffixes — `+json`, `+xml`, `+zip`, `+gzip` — so that a type like `application/vnd.example.config+json` signals both its specific format and its underlying serialization, letting generic parsers handle it without bespoke support.