What is the source of the term Use Map Settings?

Question

I heard the term "UMS" used to refer to a starcraft II custom map, and after looking it up it seems to refer to "Use Map Settings". What is the origin and history of this term?

Answer 1

The source is the original StarCraft, where the game mode for these custom maps was called "Use Map Settings":

(image from here)

It means the gameplay rules should be derived from the data in the map itself, instead of the regular StarCraft gameplay rules.