Clare. Approved Single-Engine Turbine Powered Aeroplanes, apparently now called Prescribed Single-Engine Aeroplane.
Single engine aircraft permitted to operate passenger IFR and RPT, subject to operator approval by CASA. Includes the Cessna 208 and Pilatus PC12.
Not sure why the question is being asked on the Piper Meridian, as it is a five seat turbine aircraft which does not have "commercial" payload/range capability. A pressurised Navaho with a single PT6 turbine.