A corner map is a type of map that shows the boundaries of a particular area. It is usually used to show the boundaries of a city, state, or country. The term 'corner map' comes from the fact that it typically has four corners, which represent the four cardinal directions. An INSET is a smaller map that is inserted into a larger map to provide more detail about a specific area. In this case, an INSET corner map would provide more detailed information about the boundaries of a particular area.