Hi Vincent,
I'm just beginning to learn Access security, so I'll do my best to answer
your question.
A database is always separate from .mdw files; it's not "attached" to any
particular .mdw file. You make it implicitly atrtached by creating the
appropriate groups and users (and also deactivating that infamous Admin) and
by defining permissions in the database for the groups that you have
created.
Those groups and users are unique; they exist only in your .mdw file.
Therefore, so long as you have have removed all permissions from the Admin
user and Users group (which are not unique but are replicated throughout the
world!), only the users and groups defined in your .mdw file can access the
database. In practical terms then, this database is "attached" to this .mdw
file.
I hope this answers your question. Please correct me somebody if I have got
something wrong.
Cheers,
Jerome Smith