Hi Robert! I am the Hyrax Product Owner and I think the closest thing we have right now to defined user roles for Hyrax (which is one part of the Samvera technology stack) is from the Samvera Knowledge Base:
Other Samvera software also provides user role definition as well.
Avalon Media System has the following info about collection member roles if audiovisual collection management software is what you are looking at in Samvera:
And Hyku offers a way to provide a multi-tenant Hyrax application. User roles there are tied to who can create new tenants:
I hope this info is helpful and at least points you to the various sources of documentation we have for the Samvera technology stack.
Thanks,
Julie Hardesty