Int 2F Fn 548F  U - Power.exe - Get/set ???                                [p]

   AX = 548Fh
   BX = ??? or 0000h to get current ???

Return: AX = 0000h (successful)
   BX = current ???
   CX = ???

See Also: AX=5400h,AX=5480h,AX=5482h