ofxAssimpModelLoder model orientation inverted?

I’m just getting started using ofxAssimpModelLoader. So far so good, but when I load a model, it seems to be upside down. It’s easy enough to fix using model.setRotation(2,180,0,0,1); but I’m curious as to why this is.

(I’m using an obj model created in Maya, btw - though this doesn’t seem to be related to the Flip YZ Axis issues with Obj exporting through, since I think that would cause the model to load sideways, no?)

On a related note, what’s up with the syntax for ofxAssimpModelLoader::setRotation(int which, float angle, float rot_x, float rot_y, float r_z)?
What is int which referring to exactly? And why are the last three parameters float? They seem to respond like bools as far as I can tell…