Aug 6
The numbered register "0 contains the text from the most recent yank command,
while the numbered register "1 contains the text from the most recent delete
or change command. If the delete or change was ‘small’, though, (ie, less than
one line), the small delete register "- is used instead.
This means that if you yank some text to move it elsewhere, then rearrange some
stuff (including deleting, say, newlines), you can still easily retrieve the
text that you yanked with "0p.