Edit a temporary copy of the current file
From Vim Tips Wiki
Tip 567 Printable Monobook Previous Next
created 2003 · complexity basic · author mosh · version 6.0
Edit a copy of the current file as $TMP/file-$DATE by pressing
zs using the following mapping.
:map zs :exe "sav $TMP/" . expand("%:t") . strftime("-%Y-%m-%d_%H%M%S")<CR>