Maidenhead Locator System

For specifying your location the Maidenhead locator system is used in amateur radio communication.
Any position on the earth can be described using the format AA00AA.
The first two letters define a grid field of 20 degrees longitude width by 10 degrees latitude height. A grid field is divided in 100 grid squares (10 x 10) defined by 2 numbers.
Every grid square is divided in 24 by 24 sub squares defined by two letters.

In the drawing below all 324 Maidenhead grid fields are shown.
My own location (JO21WA) is represented by the red dot on the map.