JSI Tip 0473 - Do PCL or PostScript codes print using the Line Printing Demon (LPD) service?

You can ignore format control commands for Line Printer Remote (LPR) clients and always assign the RAW datatype by editing:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LPDSVC\Parameters

Add Value name SimulatePassThrough of type REG_DWORD and set it to 1.

A data value of 0 (the default), instructs the LPD service to assign a datatype based on the control commands.