(This appendix is not part of the formal PNG specification.)
This appendix gives the locations of some Internet resources for PNG software developers. By the nature of the Internet, the list is incomplete and subject to change.
The latest released versions of this document and related information can always be found at the PNG FTP archive site, ftp://ftp.uu.net/graphics/png/. The PNG specification is available in several formats, including HTML, plain text, and PostScript.
A reference implementation in portable C is available from the PNG FTP archive site, ftp://ftp.uu.net/graphics/png/src/. The reference implementation (libpng) is freely usable in all applications, including commercial applications.
Test images are available from ftp://ftp.uu.net/graphics/png/images/.
The maintainers of the PNG specification can be contacted by e-mail at png-info@uunet.uu.net or at png-group@w3.org.
There is a World Wide Web site for PNG at http://www.libpng.org/pub/png/. This is a central location for current information about PNG and PNG-related tools.