1) The control system circuit (hydraulic, pneumatic, electrical, mechanical, or a combination thereof) used to operate the position selection of a diverter unit, BOP, valve, or regulator. Examples: diverter “close” function, starboard vent valve “open” function. 2) Each position of a diverter unit, BOP, or valve and each regulator assignment that is operated by the control system.
Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards