Register of public PNG chunks and keywords, Version 1.2.0

The latest versions of this document, the PNG specification, and related information can always be found at the PNG FTP archive site, ftp://ftp.uu.net/graphics/png/. The maintainers of the PNG specification can be contacted by e-mail at .

Abstract

This document is the register of public chunks and keywords in the Portable Network Graphics (PNG) specification, version 1.2 [PNG-1.2], plus any additional registered "public" PNG chunks and keywords, with their date of registration and location of their specifications.

Some chunks listed here are expected to be less widely supported than those defined in the basic specification. However, application authors are encouraged to use these chunk types whenever appropriate for their applications.

Additional chunk types and keywords may be proposed for inclusion in these lists by contacting the PNG specification maintainers at .

1. Register of Public PNG Chunks

This table lists the registered public PNG chunks.

   Chunk    Date       Formal specification
   type   registered   of chunk type
   
   IDAT    7 Mar 95    PNG 1.2
   IEND    7 Mar 95    PNG 1.2
   IHDR    7 Mar 95    PNG 1.2
   PLTE    7 Mar 95    PNG 1.2
   
   bKGD    7 Mar 95    PNG 1.2
   cHRM    7 Mar 95    PNG 1.2
   fRAc    7 Mar 95[1] PNGEXT 1.2.0
   gAMA    7 Mar 95    PNG 1.2
   gIFg    7 Mar 95    PNGEXT 1.2.0
   gIFt    7 Mar 95[2] PNGEXT 1.2.0
   gIFx    7 Mar 95    PNGEXT 1.2.0
   hIST    7 Mar 95    PNG 1.2
   iCCP   17 Aug 98    PNG 1.2
   iTXt    9 Feb 99    PNG 1.2
   oFFs    7 Mar 95    PNGEXT 1.2.0
   pCAL   28 Jan 97    PNGEXT 1.2.0
   pHYs    7 Mar 95    PNG 1.2
   sBIT    7 Mar 95    PNG 1.2
   sCAL    7 Mar 95    PNGEXT 1.2.0
   sPLT    9 Dec 96    PNG 1.2
   sRGB    6 Nov 96    PNG 1.2
   tEXt    7 Mar 95    PNG 1.2
   tRNS    7 Mar 95    PNG 1.2
   zTXt    7 Mar 95    PNG 1.2
   
   [1] The fRAc chunk was registered but never formally specified.
   [2] The gIFT chunk was formally deprecated on 23 Oct 98.

2. Register of Public Text Chunk Keywords

This table lists the keywords that have been registered for use in PNG textual chunks.

   Keyword           Date         Formal specification
                  registered      of keyword
   
   Title           7 Mar 95       PNG-1.2
   Author          7 Mar 95       PNG-1.2
   Description     7 Mar 95       PNG-1.2
   Copyright       7 Mar 95       PNG-1.2
   Creation Time   7 Mar 95       PNG-1.2
   Software        7 Mar 95       PNG-1.2
   Disclaimer      7 Mar 95       PNG-1.2
   Warning         7 Mar 95       PNG-1.2
   Source          7 Mar 95       PNG-1.2
   Comment         7 Mar 95       PNG-1.2

All registered textual keywords in iTXt and all other chunk types are limited to the ASCII characters A-Z, a-z, 0-9, space, and the following 20 symbols:

   ! " % & ' ( ) * + , - . / : ; < = > ? _

but not the remaining 12 symbols:

   # $ @ [ \ ] ^ ` { | } ~

This restricted set is the ISO-646 "invariant" character set [ISO-646]. These characters have the same numeric codes in all ISO character sets, including all national variants of ASCII.

3. Appendix: Revision History

4. References

[ISO/IEC-8859-1]
International Organization for Standardization and International Electrotechnical Commission, "Information Technology--8-bit Single-Byte Coded Graphic Character Sets--Part 1: Latin Alphabet No. 1", IS 8859-1, 1998.
Also see sample files at
ftp://ftp.uu.net/graphics/png/documents/iso_8859-1.*

[ISO-646]
International Organization for Standardization and International Electrotechnical Commission, "Information Technology--ISO 7-bit Coded Character Set for Information Exchange", 1991.

[PNG-1.2]
Randers-Pehrson, G., et. al., "PNG (Portable Network Graphics Format) Version 1.2", which is available at
ftp://swrinde.nde.swri.edu/pub/png/documents/.

[PNGEXT-1.2.0]
Randers-Pehrson, G., et. al., "Extensions to the PNG (Portable Network Graphics Format) Version 1.2.0", which is available at
ftp://swrinde.nde.swri.edu/pub/png/documents/.

5. Credits

Editor

Document source

This document was built from the file pngreg-master-20001121 on 21 November 2000.

Copyright Notice

Copyright © 2000 by: Glenn Randers-Pehrson

This register is being provided by the copyright holder under the following license. By obtaining, using and/or copying this register, you agree that you have read, understood, and will comply with the following terms and conditions:

Permission to use, copy, and distribute this register for any purpose and without payment of any fee or royalty is hereby granted, provided that the full text of this NOTICE appears on ALL copies of the register or portions thereof, including modifications, that you make.

THIS REGISTER IS PROVIDED "AS IS," AND COPYRIGHT HOLDER MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED. BY WAY OF EXAMPLE, BUT NOT LIMITATION, COPYRIGHT HOLDERS MAKE NO REPRESENTATIONS OR WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF THE REGISTER WILL NOT INFRINGE ANY THIRD PARTY PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS. COPYRIGHT HOLDER WILL BEAR NO LIABILITY FOR ANY USE OF THIS REGISTER.

The name and trademarks of copyright holder may NOT be used in advertising or publicity pertaining to the register without specific, written prior permission. Title to copyright in this register and any associated documentation will at all times remain with copyright holder.

End of Register of Public PNG Chunks and Keywords 1.2.0