What is rarely issued by en route controllers?

Standard Instrument Departures (SIDs) are typically not issued by en route controllers because they are specific procedures designed for departing aircraft to facilitate a safe and efficient exit from the airport environment. SIDs are generally assigned by ground control or tower controllers right before an aircraft departs, as they pertain to the departure phase of a flight. En route controllers primarily manage aircraft once they are airborne and at cruising altitude, thus their responsibilities do not usually involve the issuance of SIDs.

In contrast, flight plans are provided at the outset of a flight and serve as a record for air traffic controllers. Clearances for takeoff are provided by the tower controller to ensure safe departure from the runway. Arrival updates are issued by controllers to provide information on the aircraft's approach and landing, which is part of the en route controller's role. Thus, the other options are all within the scope of what en route controllers may handle, making SIDs the outlier.