Would anyone know what the "ID" is in this plugin command?

Orange Overlay
● ARCHIVED · READ-ONLY
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Examples:
Code:Overlay fog fog1 100 10 0 0 20
ID looks to be just a unique identifier to refer to this fog overlay later if you ever need to. -
YEP. Basically you just assign that fog layer it's own ID whenever you create it using the addfog command.
*Edit* and then using the standard fog command should reference any ID'S you created