The fourth line (TAG4) defines a special control element. It uses the key word Control followed by a name specifying the type of control element requested contained in parentheses.
The element parameter has three possible values. They are not case sensitive.
_Layer specifies the layer control element. This element is a pop-up list that controls the current layers in the drawing.
_Linetype specifies the linetype control element. This element is a pop-up list that specifies the current linetype.
_Color specifies the color control element. This element is a pop-up list that specifies the current color.