When developed drawing elevation diagrams, I added ability to show current position on path for selected elevation profile value. And for this reason I added new icons, which names started from gm#
The gm#simple-… group of icons show simple icon like in Google Maps, for definite color (… – color)
The gm#dot-… group of icons show simple icon with dot like in Google Maps, for definite color (… – color).
And the gm#cluster-… group of icons from clusterer, because there are many people ask about how change cluster icon and use the different cluster icon but clusters.