Complex sentence: The Metropolitan Police use the term Borough Operational Command Unit (BOCU) for regional units (which are based on the 32 London boroughs) and Operational Command Unit (OCU) for other units, for example the Aviation Security OCU.
Split into simpler sentences: The Metropolitan Police use the term Borough Operational Command Unit (BOCU) for regional units (which are based on the 32 London boroughs). The term Operational Command Unit (OCU) is used for specialised units, for example the Aviation Security OCU.