EOL - Permissions Level OWA
Descriptions of Calendar Permission Level using Outlook Web
Can view when I'm busy: Allows someone to view blocks of time as Free, Busy, Tentative, Away.
Can view titles and locations: Allows someone to view your Subject and Loction. Events set to private will only display as Private Appointment.
Can view all details: Allows someone to view your Subject, Location, Attendees and Description. However, any event you mark as private displays simply as Private Appointment.
Can edit: Provides read/write/modify access.
Delegate: In addition to "can edit" permissions, a delegate can also be selected to recieve calendar notifications/requests/invitations. By default, "Delegates" cannot view/modify events set to Private. You do have the option to grant the delegate the ability to view Private events.