device class: file

[Jim]

In the CUPS Software Programming Manual:
  5 - Writing Backends
    Supporting Device Discovery
http://www.cups.org/doc-1.1/spm.html#6_2_1

It states:
  CUPS currently recognizes the following classes:
    "file" - a disk file.
    "direct" - a parallel or ...
    "serial" - a variable-rate serial port.
    "network" - a network connection ....

Where can I find more docs on the Device Class "file"?

Becareful. The docs are labled "Software Programmers Manual, CUPS"
on the documentation page.

Trying to get an understanding of <device class><device URI> for device class of "file".

Thanks,

---
Jim