The documentation says ISceneCollisionManager::getSceneNodeFromRayBB ,but looking in the engine that function internally calls aabbox3d< T >::intersectsWithLine which appears to take length into account, thus the function is getting a scene node from a line, not a ray. A fairly small,but important distinction, and unless I am wrong here it should be documented differently.
BTW: I was glad to find out it tested a line of limited length, I like it better this way.