I am a Media Director who created two computer lab calendar, an ipad calendar, and laptop calendar for approximately 30 teachers. When someone creates an event in a shared calendar, others can delete the event and move it. I think as a creator of an event, you should be the only person to edit it, other than the owner of the calendar. Although it isn't frequently done, it has happened on accident when event times have been changed by others. There should be calendar owner(Can edit and delete all events), event author(or event editor that only allows you to edit or delete your own event you created), and reader.