How is the pitch angle of the IEA-15-240-RWT turbine defined?

Hello all,
we want to build the IEA-15-240-RWT wind turbine in our in-house software and compare the results with openFAST. Since this turbine is also heavily twisted, we are not sure how exactly a 0° pitch angle is defined.
Does this mean that the chord axis of the root of the twisted blade is parallel to the rotor plane? Or does this apply to the blade tip? A third possibility would be that we rotate the blade around by its twist angle of the blade root and define that as 0° pitch.
I would be very happy if someone could help me here.
Best regards

Hi @David.Maertins,

See my post dated May 19, 2017 for the definitions of pitch and twist as used by OpenFAST: Definition of parameters (the post mentions FAST, but the same definitions apply to OpenFAST).

Best regards,