Register of public PNG chunks and keywords, Version 1.4.6

   The latest versions of this document, the PNG specification, and
   related information can always be found at the PNG FTP archive site,
   [1]ftp://ftp.simplesystems.org/pub/png/. The maintainers of the PNG
   specification can be contacted by e-mail at
   [2]png-mng-misc @ lists.sourceforge.net.

Abstract

   This document is the register of public chunks and keywords in the
   Portable Network Graphics (PNG) specification, version 1.2
   [[3]PNG-1.2], and in Portable Network Graphics (PNG) Specification
   (Second Edition) [[4]PNG-ISO], 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
   [5]png-mng-misc @ lists.sourceforge.net.

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    [6]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
   dSIG    1 May 08    [7]PNGEXT 1.4.0
   fRAc    7 Mar 95[1] [8]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
   sTER   15 Apr 06    [9]PNGEXT 1.3.0
   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
   Collection     24 Jul 04       png-list archives
   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
   [[10]ISO-646]. These characters have the same numeric codes in all ISO
   character sets, including all national variants of ASCII.

3. Appendix: Revision History

     * 18 Sept 2013 (version 1.4.6): Fixed bad link.
     * 3 Aug 2008 (version 1.4.5): Added "Collection" keyword.
     * 1 May 2008 (version 1.4.0): Added dSIG chunk.
     * 30 August 2006 (version 1.3.0): Added sTER chunk. Updated some
       URLs.
     * 21 November 2000 (version 1.2.0): First public release, derived
       from the PNG Specification [PNG-1.2] and the PNG Extensions
       document [PNGEXT-1.2.0].

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
          [11]ftp://ftp.simplesystems.org/pub/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
          [12]ftp://ftp.simplesystems.org/pub/png/documents/.

   [PNG-ISO]
          "Portable Network Graphics (PNG) Specification (Second
          Edition)," 10 November 2003, also released as "International
          Standard 15948:2003 -- Portable Network Graphics (PNG):
          Functional specification", available at
          [13]http://png-mng.sourceforge.net/pub/png/spec/iso/

   [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
          [14]ftp://ftp.simplesystems.org/pub/png/documents/.

   [PNGEXT-1.3.0]
          Randers-Pehrson, G., et. al., "Extensions to the PNG (Portable
          Network Graphics Format) Version 1.3.0", which is available at
          [15]ftp://ftp.simplesystems.org/pub/png/documents/.

   [PNGEXT-1.4.0]
          Randers-Pehrson, G., et. al., "Extensions to the PNG (Portable
          Network Graphics Format) Version 1.4.0", which is available at
          [16]ftp://ftp.simplesystems.org/pub/png/documents/.

5. Credits

  Editor

     * Glenn Randers-Pehrson, glennrp @ users.sourceforge.net

  Copyright Notice

   Copyright © 2000, 2006-2008, 2013 by: Glenn Randers-Pehrson

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   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 1.4.6

References

   1. ftp://ftp.simplesystems.org/pub/png/
   2. mailto:png-mng-misc%C2%A0@%C2%A0lists.sourceforge.net
   3. file://localhost/ftp/pub/libpng/png/documents/pngreg-1.4.6-pdg.html#PNG-1.2
   4. file://localhost/ftp/pub/libpng/png/documents/pngreg-1.4.6-pdg.html#PNG-ISO
   5. file://localhost/ftp/pub/libpng/png/documents/pngreg-1.4.6-pdg.html#64;%C2%A0lists.sourceforge.net
   6. file://localhost/ftp/pub/libpng/png/documents/pngreg-1.4.6-pdg.html#PNG-1.2
   7. file://localhost/ftp/pub/libpng/png/documents/pngreg-1.4.6-pdg.html#PNGEXT-1.4.0
   8. file://localhost/ftp/pub/libpng/png/documents/pngreg-1.4.6-pdg.html#PNGEXT-1.2.0
   9. file://localhost/ftp/pub/libpng/png/documents/pngreg-1.4.6-pdg.html#PNGEXT-1.3.0
  10. file://localhost/ftp/pub/libpng/png/documents/pngreg-1.4.6-pdg.html#ISO-646
  11. ftp://ftp.simplesystems.org/pub/png/documents/
  12. ftp://ftp.simplesystems.org/pub/png/documents/
  13. http://png-mng.sourceforge.net/pub/png/spec/iso/
  14. ftp://ftp.simplesystems.org/pub/png/documents/
  15. ftp://ftp.simplesystems.org/pub/png/documents/
  16. ftp://ftp.simplesystems.org/pub/png/documents/