On the phone ap, when you select an area and inquire, it explains them. I haven't found a legend, so to speak. I found on the web app you can inspect the code, might be able to find one if you are a programmer...
2015 Skeeter FX 21
...and down goes PhotoBucket with the new Terms of Service... I predict they will be out of business or begging for forgiveness inside a month. 6/30/2017