Both numbers are internal, legislative designations and are thus unsigned.

It is also known by Alfa Romeo's internal designation 916.

Nissan's internal designation for this model was R20.

Designers and manufacturers also had their own internal designations which could be confused for the official government designations.

The 770 was substantially revised in 1938, resulting in the new internal designation of W150.

You said, "Well, all they have to do is change the 51 to 10," which is of course an internal designation.

The first prototype, with the internal designation of T, made its first flight on 11 June 1941.

In 1913 the engine capacity was increased to 3969 cc and the internal designation changed to C. Production continued until 1915.

Boeing gave the aircraft the internal designation of Model 717.

Handley Page's design in response to B.35/46 was given the internal designation of HP.80.