Indicates the type of map layer you are creating. Fill layers will always be drawn beneath markings layers.
|xplm_MapLayer_Fill||"0"||A layer that draws "fill" graphics, like weather patterns, terrain, etc. Fill layers frequently cover a large portion of the visible map area.|
|xplm_MapLayer_Markings||"1"||A layer that provides markings for particular map features, like NAVAIDs, airports, etc. Even dense markings layers cover a small portion of the total map area.|