April 28, 2014, 12:12:27 am
There is no standard, some 3d applications use Y as up, some use Z as Up.
So long as the export/import converts from one to the other when required, then the object will be correct. When users refer to the axis, it does help to qualify the axis as Up or Forward to help others understand.
There's also two general rotational types, left handed, and right handed. Again some applications use one, some use the other.