ANSI Common Lisp 22 Printer 22.1 The Lisp Printer 22.1.3 Default Print-Object Methods
220.127.116.11 Printing Pathnames
When printer escaping is enabled,
the syntax #P"..." is how a
pathname is printed by write and the other functions herein described.
The "..." is the namestring representation of the pathname.
When printer escaping is disabled,
write writes a pathname P
by writing (namestring P) instead.
For information on how the Lisp reader parses pathnames,
see Section 18.104.22.168 Sharpsign P.