A couple of 5.3 questions

[Francisco Reyes]

Plan to soon move to 5.3 through a backup, fresh install proces..

One of the main reasons I am moving is for the snapshot capability.
Reading the man for MKSNAP_FFS(8) I see
mksnap_ffs mountpoint snapshot_name

Question: Does mountpoint has to be a filesystem or can it be a directory?
For example if I have:
/
/usr
/var

Can I make a snapshot of /usr/home? Or I can only do /usr?

Then I went on to look at how to mount snapshopts, and although found the 
info, got a little more confused.

The mount command has in the man page:
snapshot
This option allows a snapshot of the specified
file system to be taken.

So is mount or mksnap_ffs that makes the snapshot?

The only reason I am trying to get this info is to know if to make a 
separate filesystem for files I would like to snapshot.