[GRASSLIST:7972] dead lines?

[M S]

I read that v.clean "removes dead lines from your map.  Dead lines are
vectors that have been marked for deleted in v.digit."

I'm confused about these dead lines.  In v.digit (using grass 6.0) i
delete lines and they go away, and then i get prompted to remove the
associated record from the database.

Are these lines really deleted at this point?

It sounds like they are not removed until v.clean is run.  if this is
the case, can these lines be restored PRIOR to running v.clean?

Can someone rephrase  what v.clean does and what "dead lines" are?

thanks!