authenticated user: everybody who needs to add content to the site. This probably includes interns or so who should only be able to add and edit content, but who can't take decisions about categories or which negotiation counts is to be flagged as "current"
Site admin/ editor : experienced users who can take decisions about new categories, which meeting is current, and who can add accounts for new users.
Tech admin: users who can change some configuration, such as adding a new language for translations when needed.