Schedule has three pre-defined roles that cannot be disabled, Administrator, Dispatcher, and View Only. You can create additional roles for your users, but a user can only be assigned to one role.

Pre-Defined Roles

• Administrator
  Has all View/Edit/Delete permissions. Some of the Delete permissions are not available as these are created in Service Management.
• Dispatcher
  Has View/Edit permissions and you can select specific Delete permissions.
• View Only
  This role has only View permissions.

...