These filters are legacy, and are provided for reference purposes.
Your milage may vary. You should check to make sure that they
compile and run. No other documentation available.
You will have to read the source code to figure out what they do
pfilter - (obsolete - see ifhp filter)
The code contained in this distribution defines a filter designed
specifically for the Tektronix Phaser 560 printer line. The filter
is designed to work with LPRng as created and maintained by
Patrick Powell. The filter was developed under version 3.5.1
of LPRng.
schlake - (obsolete - see ifhp filter)
Very interesting method to massage recalcritant PostScript files
and make then run on Phaser 560.
tek - APPSOCKET connection filter
Interesting descriptions of how the UDP socket communication
support is implemented.