There is a Model 'type' that defines a fixture's 'whip'/power input cord.....called "Pigtail", under Geometry--Primitives--Pigtail. That should be enough? I doubt that there will be an Attribute for that however[Fixture Orientation??]...I could be wrong?!? Build your 3D models to real world fixture behavior, some Yokes are 90 degrees offset from 'Pigtail' position, some aren't. I know I always ask the Programmer how they prefer the fixtures positioned.