The Service Depot is a building where a vehicle or an aircraft can enter in order to repair itself for a small fee.
The service depot is usually a requirement for the expansion tactic, because it is needed to produce new MCVs.
Destroying both an enemy's service depot and Construction Yard (or an enemy's War Factory and Construction Yard) means they can no longer produce MCVs and are never able to build structures again.
An aircraft and a vehicle can be on a Service Depot at the same time.
Prerequisites[]
Loosely speaking, the Radar Dome is a prerequisite for "range or technology oriented" units, whilst the Service Depot is a prerequisite for "heavy or mechanically oriented" units.
The service depot is a prerequisite for following: