[Dovecot] format of file dict

[Frank Cusack]

For shared (between users) mailboxes, I am using a file dict.

plugin {
  acl_shared_dict = file:/etc/dovecot/acl_shared_dict/shared.db
}

What is the format of this file?  I would like to manage it directly
rather than have SETACL update it.  I see lines which describe a
sharing entry (the format of those looks obvious) but also lines
with just a '1'.

Do I just need to separate entries by lines with just '1' in them?

-frank