CALLISTO V2 (serv.man8). Using the Callisto Version 2 Configuration Manager - Sharp Copying Equipment User Guide / Operation Manual. Page 7

The Network Administrator has considerable control when defining how print jobs are
distributed across Output Queues. The decision algorithm uses several threshold
parameters for resolving which of the Output Queues the print job is ultimately sent. For
example, the Input Queue has Split By Copy Count where a job can be split over a number
of printers.

Thresholds also define the operating parameters of the Output Queues. A typical
parameter would be Exclusion Rule: Maximum Page Count where a printer would be
excluded if the number of pages in a print job exceeded this value.

Since printers have differing capabilities such as speed, colour, duplex etc. each Output
Queue can be set with different parameters so the full potential of the physical devices can
be realised.

During the installation phase of Callisto, a virtual port is created in the Windows
environment. This virtual port is called Callisto. This virtual port is, in effect, a dummy
port that tells Windows to do nothing with any print jobs it receives. An Input Queue uses
this virtual port to guarantee that the printer is virtual.