Returns the long form of a namestring.
long-namestring pathname => result
A pathname designator.
A string or
long-namestring first obtains the full namestring as if by
cl:namestring, and then converts this namestring to the long form (in the Microsoft Windows meaning of "Long" paths).
If the translation succeeds then result is a string in the Long form.
The translation may fail, in which case
nil is returned.
LispWorks User Guide and Reference Manual - 20 Sep 2017