PostScript Level 2 does offer CCITT (now ITU-T) Group 3 and Group 4
encoding and decoding filters. PostScript language support for the ITU-T
Group 3 and Group 4 standards is limited to encoding and decoding of image
data. It does not include initial connection and handshaking╩protocols that
would be required to communicate with a fax machine. The purpose of these
filters is to enable╩efficient interchange of bi-level sampled images
between an application program and a PostScript interpreter. For more
information,╩please see pages 134 to 136 in the "PostScript Language
Reference Manual, Second Edition" (ISBN 0-201-18127-4) from Addison-Wesley.
The LaserWriter Pro 810 and LaserWriter Select 360 have fax options that
use the PostScript Level 2 ITU-T Group 3 encoding and decoding filters.