Service Overrides
At run time; each property read, property write, event execution, and service execution can have explicit overrides. This allows you to grant or deny specific capabilities to any group or user to meet a specific need.
To access the serviced overrides, go to the entity list, select a specific entity, and enter the security editor for that entity. In the run time view, there is an override link for each action mentioned above. Click that link to access a list of specific events, properties, and services for that entity. You can then assign an explicit grant or denial for any action.