Standards
It is important that track and stock conform to the Wheel Profile, Track Gauge, and Running Gauge standards. The buffing and drawgear standards should be treated as recommendations for anyone not working to accurately scaled full size dimensions, eg if your prototype had slightly shorter buffers or longer couplings, that would not make the model incompatible and would be acceptable. If you are unsure what the full size dimensions were, you can use the standards.
Below are links to the six standards so far agreed.