As it's coded by Mladen it's a Guppy indicator that can be relied on. Thanks to Mladen for making this back in the day

As explained by Mladen:
T3 GMMA
For short (shorter periods - faster) part set the ShowLongGmma parameter to false. For long (longer periods - slower) set it to true and the, by combining the 2 you can get something like this (quoted post attached above with image).