N.D. Cent. Code § 47-08-02: Principal part defined

The principal part shall mean that part to which the other has been united only for the use, ornament, or completion of the former, unless the latter is the more valuable and has been united without the knowledge of its owner, who in the latter case, may require it to be separated and returned to the owner, although some injury should result to the thing to which it has been united. If neither part can be considered the principal part, the more valuable, or if the values are nearly equal, the more considerable in bulk, is to be deemed the principal part.