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Network Working Group
Request for Comments: 3073
Category: Informational
J. Collins
Bitstream Inc.
March 2001

Portable Font Resource (PFR) - application/font-tdpfr

MIME Sub-type Registration

Status of this Memo

This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.

Copyright Notice

Copyright © The Internet Society (2001). All Rights Reserved.

Abstract

This document describes the registration of the Multipurpose Internet Mail Extensions (MIME) sub-type application/font-tdpfr. The encoding is defined by the PFR Specification.

A Portable Font Resource (PFR) contains a set of glyph shapes. Each glyph shape is associated with a character code. The PFR format is designed to be both compact and platform-independent. It is intended to facilitate accurate rendering of fonts in all environments whether or not they have the required fonts already installed.

1. Conventions used in this document

The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [REQ].

2. Overview

This document describes the registration of the MIME sub-type application/font-tdpfr. The encoding is defined by [PFR].

3. PFR Definition

PFR (Portable Font Resource) is defined by Bitstream Inc. in [PFR]. The documentation can be obtained from Bitstream at: 

   Bitstream Inc.
   215 First Street
   Cambridge MA 02142 U.S.A.
   Phone: +1 617 497 6222
   Fax:   +1 617 868 0784

A copy of this specification can also be found at: 

   http://www.bitstream.com/pfrspec/index.html

While a brief scope and feature description is provided in this section as background information, the reader is directed to the original PFR specification [PFR] to obtain complete feature and technical details.

3.1 PFR Scope

A PFR contains a set of glyph shapes. Each glyph shape is associated with a character code. The PFR format is designed to be both compact and platform-independent. It is intended to facilitate accurate rendering of fonts in environments whether or not they have the required fonts already installed.

The glyph shape definitions in a PFR are resolution-independent. This allows glyph definitions to be displayed or printed on devices with a wide variety of resolutions. It also allows glyphs to be rendered at any size.

3.2 PFR Features

Some of the features of the PFR format are:

  • Compact representation of glyph shapes
  • Independent of byte order and operating system
  • Independent of output device resolution
  • Fully scalable to any glyph size
  • Optional inclusion of bitmap glyph images
  • Adopted as the font standard by DAVIC, DVB, and DTG

4. Comments

This document is submitted by J. Collins, Bitstream Inc. All comments should be directed to <jcollins@bitstream.com>.

5. MIME Definition

The PFR media type has been previously registered with IANA as application/vnd.truedoc. In view of its subsequent widespread adoption as a standard font format by multiple standards bodies who have relationships with the Internet community, Bitstream has been asked to re-register this media type within the IETF tree.

6. IANA Registration

   To: ietf-types@iana.org
   Subject: Registration of Standard MIME Media type
       application/font-tdpfr

MIME media type name: application

MIME subtype name: font-tdpfr 

   Required parameters: none
   
   Optional parameters: none

Encoding considerations: Binary or base 64 required

Security considerations:

PFR uses a structure that can store glyph image data and encoding arrays. The fields defined in the PFR specification are of a descriptive nature and provide information that is useful to facilitate viewing and rendering of glyph images by a recipient. As such, the fields currently defined in the PFR specification do not in themselves create additional security risks, since the fields are not used to induce any particular behavior by the recipient application.

PFR has an extensible structure, so that it is theoretically possible that fields could be defined in the future which could be used to induce particular actions on the part of the recipient, thus presenting additional security risks, but this type of capability is not supported in the referenced PFR specification. Indeed, the definition of fields that would include such processing instructions is inconsistent with the goals and spirit of the PFR specification. 

   Interoperability considerations: none

Published specification:

The specification for this content type is available on request from: 

      Bitstream Inc.
      215 First Street
      Cambridge MA 02142 U.S.A.
      Phone: +1 617 497 6222
      Fax:   +1 617 868 0784

A copy of this specification can also be found at: 

      http://www.bitstream.com/pfrspec/index.html

Applications which use this media type:

Netscape Communicator, Bitstream WebFont Maker, Hexmac Typograph 

   Additional information: None

Magic number(s): 50 46 52 30 hex 

   File extension(s): PFR
   
   Macintosh File Type Code(s): Creator: 'b$pw' Type: 'PFR '

Person to contact for further information: 

      "John Collins" <jcollins@bitstream.com>
   
   Intended usage: common

Author/Change controller: 

      "John Collins" <jcollins@bitstream.com>

7. References

   [REQ]   Bradner, S., "Key words for use in RFCs to Indicate
           Requirement Levels", BCP 14, RFC 2119, March 1997.
   
   [MIME1] Freed, N. and N. Borenstein,  "Multipurpose Internet Mail
           Extensions (MIME) Part One: Format of Internet Message
           Bodies", RFC 2045, November 1996.
   
   [MIME4] Freed, N. and N. Borenstein,  "Multipurpose Internet Mail
           Extensions (MIME) Part Four: Registration Procedures", RFC
           2048, November 1996.
   
   [PFR]   Bitstream Inc. "PFR Specification",
           http://www.bitstream.com/pfrspec/index.html

8. Author's Address

John Collins
Bitstream Inc.
215 First Street
Cambridge, MA 02142 

   Phone: +1 617 520 8401
   Fax:   +1 617 868 0784
   EMail: jcollins@bitstream.com

9. Full Copyright Statement

Copyright © The Internet Society (2001). All Rights Reserved.

This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English.

The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

Funding for the RFC Editor function is currently provided by the Internet Society.