What is this RGB color map for?

So I found this coloued map from some game files, It appears to be for highlights or refelction in some way. As the yellow/red areas would be shiny and the lighter blue areas should reflect more light than the darker blue. Other option is that its a height map in some way,but I doubt that as the blue cross on the button would be higher than the button itself.

I am wondering:

1. What type of map is this?

2. How to use this map or at least a point in the right direction.