Q3. What is a print queue?

A3. A print queue is a queue in which print jobs wait inside an image controller to be printed.

If you use Image Controller IC-415 or Image Controller IC-308 and select "Scan to Hold Queue", you can treat scan data as print jobs. There is the advantage of being able to apply image controller functions to data.
Example: Color Management settings, and so on
For details, refer to Overview of Scan to Hold Queue.