Windows NT supports UNIX printing clients by providing the TCP/IP Print Server (LPD) service. This service can receive print jobs from UNIX systems or other operating systems—including Windows NT—that have LPR client software. The client software must support RFC 1179. This is problematic, because many systems do not support this specification. Others that claim to support it do not implement it entirely, or they supply private extensions to the specification that their users have come to rely on but that don't exist except on that system. For more information about how to correct problems printing from systems that don't comply with RFC 1179, see "Line Printer Monitor (Lpdmon.dll)" later in this chapter.
The LPR protocol does not pass detailed error status information back to the LPR client. If anything goes wrong, from severe problems (such as the server being too busy to process requests) to print device problems (such as running out of paper), the LPR protocol reports the same error condition.