"MFR Model Codes" from VIN decoder
 

Hello,
I have looked and looked and I can't find any information regarding the MFR model codes that pop up in the VIN decoder elsewhere on this site. For example- the VIN# WMWZC5C55DWM15222 gives a model code 13ML and I get that the 13 is a model year, but what is the rest? And as I am shopping for a mini, where do I find data regarding these various codes? Thanks, mini people!