The currently selected service's Id.
Setting the Service property to the Id of a discovered service allows you to inspect the characteristics which have been discovered for it using the Characteristic* properties.
Service can either be set to the Id of a service which has been discovered for the currently connected server, or to empty string. Setting Service will automatically reset Characteristic to empty string.
This property is automatically set when you call the Select method.
This property is not available at design time.