Hi Donna,
AtoM does have basic multi-repository functionality, but not for all entities that you mention. Essentially, AtoM supports multi-repository access, but not full multi-tenancy, where every institution's records are hidden from other institutional users and each institution has a logged in experience as if they were in their own installation.
To clarify further:
An archival description can be associated with different repositories, and permissions can be used to keep access to them separate from other institutional users.
Authority records can have one maintaining institution, but be used by many different repositories.
All other entities at this time are shared for logged in users. There is currently no way to separate by repository access to entities such as:
- Accession records
- Donors
- Subject, Place, and Genre access point terms
- Physical storage records
- Rightsholder records
- etc
Unfortunately, to gain the kind of separation you are looking for you would currently have to do the same thing with AtoM that you are doing with CALM - that is, keep separate installations, and then send descriptions to a centralized public access catalog.
There are examples of institutions who have developed their own custom solution - for example, the St. John's College Archives at the University of Cambridge built its own lightweight custom front end that combines searching across 2 separate AtoM instances (one for Institutional Archives and one for Personal Papers).
Alternatively, many Canadian provinces and territories, full of underfunded archives, simply use one shared AtoM instance for managing descriptions, and authorities, and either do not use or else use their own private local tools for non-public records such as accessions, donors, etc. For example, the Archeion portal for Ontario - the portal administrators developed a controlled vocabulary of Ontario place terms for all to share as well:
If you'd like a chance to explore AtoM yourself in a hands-on way to determine if it can meet your needs, there is a public demo site that resets hourly you can play with here:
Log in credentials are listed on the homepage. Note that uploads of all kinds are disabled for security purposes.
Cheers,