This specification, together with the Purchase Order, GCC or Proponent’s Instrument Specification Sheets (ISSs) , GCC or Proponent’s Non Material Requirements Number (xxxxx) and GCC or Proponent’s Inspection Requirements Forms define the minimum mandatory requirements for general service pneumatically operated steel control valves up to and including Class 2500 ratings. This specification is not applicable to on/off valves. Commentary Note: Some control valves are used in on/off service or interlock applications. Such valves are part of the scope of this standard.