Ideal Ice Level

Styrofoam cupOn the side of a familiarly-branded foam cup, this small icon was spotted (sorry for the blurry picture).

It appears to be an indicator of how much ice to fill the cup with. Can you figure out any other meaning behind this icon?

If it is an “ideal ice level” indicator, I wonder how the cup maker decided what was the ideal amount.

Is it based on an average assumed beverage consumption rate?

Is it trying to ensure that an average consumer will imbibe the majority of their drink at some ideal temperature which provides maximum enjoyment?