A Gate is a 'service window' which describes the entry point of the gate and what size package is passed into the more protected ring.
----------------------------------------------- | RING 3 | | -------------------\ -------------- | | | \ <--- Gate | | | | RING 2 \ | | | | ------\ ----------------- | | | | | \ <--- Gate | | | | | | \ | | | | | | RING 0 | | | | | | | | | | | | | | | | | -------------------------- | | | | | | | ------------------------------------ | | | -----------------------------------------------