usb: device and kpilot

[Jesus Arocho]

After a week of trying to get kpilot to recognize my Zire 31 on a kubuntu box 
I installed gnome-pilot.  I had mappled /dev/pilot to the appropriate 
location: /dev/bus/usb/usb3 as indicated by dmseg.  After several tries with 
usb ports I noticed 'usb:' as an option.  I tried it and it worked.  I went 
back to kpilot added usb: and it then also recognized the Zire 31 and kpilot 
added the data to kontact.

Question: what is 'usb:' ?  It does not show up in /dev as a device, at least 
it is not obvious.