On 09/05/2014 11:39 AM, Achim Gratz wrote:
> Stefan Monnier writes:
>> When can variable refs be of the form %name or !name
>> (i.e. without the terminating % or !)?
> 
> These are so-called parameter variables; more specifically loop
> variables and arguments, these must be single alpha character or
> numerical.  There are also local variables when you enable extended
> syntax, but they localize the environment variables and thus keep their
> syntax.
> 
> I think that's the best syntax description (and most concise) I've found
> so far:
> 

Mind just importing http://www.emacswiki.org/emacs/ntcmd.el into trunk?
It handles a bunch of nasty cmd.exe syntactic corner cases.