what is the device.map used for ?

[John Lumby]

Not a bug, not even a problem - just curious.

I understand what the device.map is and how to specify it,  but I have yet 
to come across something that uses it;    by which I mean, something such as 
a subcommand whose syntax includes a reference to a device in unix /dev/xxx 
form and then reverse-looks up that unix device name in device.map to get 
the BIOS name;  or a subcommand which accepts the BIOS form and then needs 
for some reason (what?) to find the unix name.

I guess maybe it's used when running the unix command grub?   Since then the 
unix devices do exist.    But I also guess it's never used when grub runs 
stand-alone from initial boot?

John