Understanding chinese motor codes

[Puffie40]

I've been looking at some electronic motor codes and want to try to understand them. 

An example:
50TKYJ24-4-553
35BYJ412P

So far I have determined that the first two numbers are the outside diameter of the motor in millimeters (50mm and 35mm respectively), and the numbers in the middle are an indication of the operating voltage (24V and 12V respectively).

The 35BYJ412P motor has 5 wires, so is likely a unipolar stepper motor and maybe referenced by the 4.  The 50TKYJ24-4-553 motor, according to AliExpress searches(https://goot-motor.en.alibaba.com/product/60640667632-801270118/Multifunctional_ac_permanent_magnet_synchronous_motor_for_wholesales.html), is a synchronous motor, and the "-4-" is likely a reference to the RPM.

So the mystery is the letters in the motor code. is there a reference for determining what kind of motor I have?

Thanks!