Which to use?
The distinction may also help clarify
- m is a member during v Member(m,v)
- m enrolls at time e Enroll(m,e)
- m resigns at time e Resign(m,e)
This approach may lead to confusion
- Must you be a member to enroll?
- Are you a member after you resign?
Instead define membership in terms of the enrolls and resigns designations