Each custom made calendar (my calendar) has the option to be shared with other system users. Clicking on the gear icon opens a popup with options for sharing. By clicking the set button, you can choose to share the calendar with all system users or with specific users belonging to a particular scope. Shared with me calendar will show every calendar which another system user has shared with me.
Sharing options popup
Accessing permissions within the particular scope can be done as described in the section Scope Management.