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HTTP: The Definitive Guide

Cover of HTTP: The Definitive Guide by David Gourley... Published by O'Reilly Media, Inc.
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MIME Type IANA Registration

The MIME media type registration process is described in RFC 2048. The goal of the registration process is to make it easy to register new media types but also to provide some sanity checking to make sure the new types are well thought out.

Registration Trees

MIME type tokens are split into four classes, called "registration trees," each with its own registration rules. The four trees—IETF, vendor, personal, and experimental—are described in Table D-2.

Table D-2. Four MIME media type registration trees

Registration tree





(HTML text)

The IETF tree is intended for types that are of general significance to the Internet community. New IETF tree media types require approval by the Internet Engineering Steering Group (IESG) and an accompanying standards-track RFC.

IETF tree types have no periods (.) in tokens.




(Kodak FlashPix image)

The vendor tree is intended for media types used by commercially available products. Public review of new vendor types is encouraged but not required.

Vendor tree types begin with "vnd.".




(internal check-management format used by Nations Bank)

Private, personal, or vanity media types can be registered in the personal tree. These media types will not be distributed commercially.

Personal tree types begin with "prs.".


(x- or x.)


(Unix tar archive)

The experimental tree is for unregistered ...

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