Usually on a flat map of the world the international date line is the left and right (west and east) edges of the map, but it is clearly marked on a globe.
It is known as the International Date Line.
The International Date Line zigzags to accommodate national boundaries and avoid dividing countries in half. It appears on both sides of the map because it is not a straight line; it bends to include certain territories within the same date.
Alaska. A small Alaskan island in the Pacific is the cutoff for the dateline. If you look on a map showing the date line, you'll see the dateline swerves in order to accommodate the US national boundary.
Map showing the location of Assam in India with state and international boudaries.
An agonic line is a line on a chart or map showing points of zero magnetic declination.
A contour map is a physical map showing elevation and each line shows a major change in elevation.
Scale Bar
The scale of contour lines on a topographic (terrain) map is called the "contour interval".
The two broken lines on a world map are called the International Date Line and the Tropics of Cancer and Capricorn. The International Date Line, located at approximately 180 degrees longitude, serves as the boundary for calendar dates. The Tropics of Cancer and Capricorn mark the northern and southern boundaries of the tropics, indicating the furthest points north and south where the sun can be directly overhead.
The International Date Line is an imaginary line running from the North Pole to the South Pole, mostly along the 180° line of longitude in the Pacific Ocean. It serves as the divide between two calendar days.
The International Date Line is drawn on a map to mark the point where each day officially begins. It is an imaginary line that runs from the North Pole to the South Pole and helps to account for the differences in time zones and days around the world. It ensures that as you cross it, you either gain a day or lose a day depending on the direction of travel.
Here is a link to a map http://www.sonofthesouth.net/slavery/slave-maps/mason-dixon-line.htm