what is a vpath

System

I always thought a vpath was a device-independant specification for a file in the IFS. I always throught the vpath for something like Y:\default\main\WORKAREA\work\dir\file would be /default/main/WORKAREA/work/dir/file. But when I invoke show_env.cgi it says the vpath is more like \default\main\WORKAREA\work\dir\file. So I am left wondering, what is a vpath? Is it an OS path without the Interwoven virtual device mount, or something else?