The Sharing Page should say what each Role means

(Incomplete Feature, Investigate , Priority: Critical, Test Status: No automated tests yet , Reported By Bad Link: Thing 3y284oe not found, )

UX, Security, Client

Summary: Currently, the selection of Roles, during invitation, is a bit opaque.

How should this work? This is one of those places where some explicit in-context Help (eg, a "?" icon next to the selector) seems very appropriate. Want the new Help system, dammit!