X3D MIME-Type

Current work

The Internet Engineering Task Force (IETF) has approved IETF RFC 2077 for the Model MIME type. However, the IETF has not recognized X3D has an official MIME type. This page is where we are building the application message for official status.

The work started in 2008 with the initial submission at the end of the year. Comments were received from IETF MIME-Type task force and incorporated back into the application in February 2009. Comments were collected and reported regarding Registration of media type model/x3d+XXX. Further work is still needed to resubmit the application.

The February 2009 document is below. All edits need to be done in conformance with the current application standard. When completed, the application needs to be sent to 'ietf-types@iana.org' with the subject lilne "Registration of media type model/x3d+XXX" included.

Work needing to be done:

• Ensure that this is the correct format for the application
• "Encoding considerations" to update the binary encoding to current state
• Update all specification references to the latest version and description

References:

• IETF RFC 2077, The Model Primary Content Type for Multipurpose Internet Mail Extensions
• X3D MIME Types and File Extensions
• 19776-1 X3D XML encoding, 4.4.1 File extension and MIME types
• 19776-2 ClassicVrml encoding, 4.4.1 File extension and MIME type
• 19776-3: Compressed binary encoding, 4.5.2 File extensions and MIME types
• MIME Type Submission Form

Draft registration application for X3D MIME type

Type name: model

Subtype names: x3d-vrml x3d+xml x3d+fastinfoset

Required parameters: None

Optional parameters: None

Encoding considerations: This application represents the different MIME types used for three different encodings of the X3D ISO standard (see [1]). The standard defines an abstract information structural representation, for which several file formats are available. These formats are currently defined to be:

VRML-Classic: (old-style curly brace format of the VRML97 ISO standard). UTF-8 (8-bit text) is to be supported. The recently introduced UTF-8 BOM cannot be supported by definition of the specification.

XML: Encoding requirements as per the XML standards.

Binary: (Effectively a binary XML encoding scheme based on the outcome of the W3C binary XML working group process). Still a work in progress and standardisation is not yet complete.

Each content type may have an addition Content-Encoding to indicate whether the content has been compressed using GZIP in addition to the basic textual encoding. This is also indicated by modifying each file extension with the character "z". For example, the plaintext VRML-encoded file format would use the extension ".x3dv", and if compressed using GZIP uses the extension ".x3dvz"

Security considerations: Scripting is defined as being available for the specification. Two languages are defined: Java and ECMAScript. Each scripting language is controlled by its local security model. As the content may run in many different situations, the X3D specification does not impose specific security policies. For example, some standalone applications will want to directly interact with the local file system, network or database, while others that run in a web browser would use the web-browser's security model.

Interoperability considerations: The definition of the file format is maintained by the Web3d Consortium (http://www.web3d.org) and published through the ISO process. Several revisions of the specification have been made and it continues to be made. All revisions use the same MIME type definitions, and are backwards compatible internally and structurally. In addition, each of the file format encodings may be losslessly transformed between each other.

Published specification: All revisions of the X3D specification can be found here: http://www.web3d.org/realtime-3d/specification/all

Several revisions of each specification exist. The abstract specification is ISO/IEC 19775:2004. The individual file formats, which also specify the matching MIME types, are parts of the ISO/IEC 19777 specification.

Applications that use this media type: There are well over 20 - both browsers, exporters and importers.

Additional information:

Magic number(s): x3d-vrml: “#X3D” x3d+xml: Use XML’s specification x3d+fastinfoset: “#X3D”

File extension(s): x3d-vrml: .x3dv, .x3dvz x3d+xml: .x3d, .x3dz x3d+fastinfoset: .x3db

Macintosh file type code(s):

Person & email address to contact for further information: Leonard Daly (X3D Working Group Co-Chair) <email address>

Intended usage: COMMON

Restrictions on usage: None

Author: The Web3D Consortium

Change controller: The Web3D Consortium

The X3D standard is a continuation of the VRML standard that is defined in RFC2077. As part of this work, several large modifications were made to the file format and specification. The basic premise for the specification continues the VRML philosophy. The MIME types and file extensions were changed to indicate this modified standard.