Print appliance device type - manufacturer independent.
An 'xcmHrDevicePrintAppliance' is a network printing appliance
with 'xcmHrDevInfoRealization' of 'physical'.
An 'xcmHrDevicePrintAppliance' SHALL statically and/or actively
discover available network printers and SHOULD advertise them
as supported output devices, using rows in 'hrDeviceTable' of
IETF HR MIB (RFC 2790) and 'prtGeneralTable' of the Printer MIB
(RFC 1759 or successor), with 'hrDeviceType' set to
'hrDevicePrinter'.
An 'xcmHrDevicePrintAppliance' SHALL NOT use 'hrDeviceIndex' of
'1' (first row) for an 'hrDevicePrinter' row, because a network
printing appliance is an enhanced spooler and NOT a printer.