It is an Engineering code.......
Prince uses
TX141A-100 7TY73 <W> to id the frame.
I have a Pro Stock, it has the custom lenght after the head size but before the layup. I have a pre-production Speedport Blue, it has a 7*#### layup code,that is different from the retail. The TX # tell you the mold and is useful when ordering replacement bumpers.