The following information is provided as is, and the authors take no responsibility for the correctness.
The Common Printer Access Protocol (CPAP) is an application layer protocol designed to layer on any network protocol suite which supports multiple virtual circuits. It specifies the encoding of messages passed between a print service and a shared printer.
Developed by Digital Equipment Corporation (DEC)
Some reference documentation can be found on the Lexmark FTP site: ftp://ftp.lexmark.com/