The print commands use the BSD printing protocol. One of the big advantages of this protocol is that it can communicate with a variety of print servers:
SunOS 4.1 BSD (LPD) print servers
SunOS 5.8 and compatible SVR4 (LP) print servers
Any other print server or printer that accepts the BSD printing protocol
The BSD printing protocol is an industry standard. It is widely used and it provides compatibility between different types of systems from various manufacturers. Sun has chosen to support the BSD printing protocol to provide interoperability in the future.