To better understand glyph management and the year designation scheme, move control button left or right to see the Native counting mechanism in action.  Move button right and time moves forward.  Move button left and time moves backward.  The further right or left increases the rotation speed.  Click button anytime to STOP and re-START.    You can also enter a specific date and have the Native date calculated for you. 
               :     Aztec Calendar Handbook is the source material for animation programming.