do formats of vpath and auto variable file names always agree?

[Mark Galeck (CW)]

Hello,  

It says in the manual:

$<
        The name of the first prerequisite


Is it guaranteed that, if vpath is used, then the directory part of the value 
of $< is in fact, one of the vpath paths?  

(it could be, that the value of $< were an absolute path for example, while 
vpath paths are relative - is this kind of thing guaranteed not to happen?).

What about the separator between the directory path and the file name, is it 
guaranteed to always be "/", even on Windows?

Similar questions about other auto variables that depend on vpath/VPATH.  

If these things are guaranteed, can they be put in the manual?  

Mark