Returns the short form of a namestring.
short-namestring pathname => result
A pathname designator.
A string or
short-namestring first obtains the full namestring as if by
cl:namestring, and then converts this namestring to the short form (in the Microsoft Windows meaning of "Short" paths).
If the translation succeeds then result is a string in the short form.
The translation may fail, in which case
nil is returned.
LispWorks User Guide and Reference Manual - 13 Feb 2015