The buttons that may be clicked, etc. on a mouse. These can be cmobined together as a binary value to represent chording. Scroll wheels are included.
Modifiers are special keys that when combined with other keys change their meaning.
MouseEnable are the different modes that can be enabled for mouse tracking. The flagse can be OR'd together (except disable which should be used alone).
MouseEvent represents a single pressed key, possibly with modifiers. It is sent on either mouse up or mouse down events. It is also sent on mouse motion events - if the terminal supports it.