creating snapshot capable ufs2 filesystems _after the fact_

[user]

I was just looking at the man page for newfs, and the new "-n" option
... basically if you newfs with -n, a .snap directory is not created in
the new filesystem, and thus that new filesystem will not support
snapshots.

Does this mean that if I simply `mkdir .snap` in the root of a filesystem
that suddenly it is snapshot capable ?  That is to say, is that .snap
directory simply a plain old directory, and having a ufs2 filesystem
support or not support snapshots is only dependent on simply having that
directory in place ?

Or is there more to .snap and to the -n option ?