It is documented.
Quoting Timothy Madden <firstname.lastname@example.org>:
>> You can use "cmd //C myscript.bat", "//" gets converted to "/".
>> As for documentation, sorry, its mostly my personal experience, but you
>> can always start with google. You may want to use escape characters like
>> an extra "/" like the above "//".
>> btw, can you avoid top-posting? thanks.
>> Yes, sorry.
> Great tip.
> Too bad it is not documented.