Tetrad (unit of area)
From Wikipedia, the free encyclopedia
A tetrad is an area 2km x 2km square.
The term has a particular use in connection with the British Ordnance Survey national grid, and then refers to any of the 25 such squares which make up a standard hectad. These are numbered from A to Z according the "DINTY" system as shown in the grid below (taking its name from the second line).
| E | J | P | U | Z |
| D | I | N | T | Y |
| C | H | M | S | X |
| B | G | L | R | W |
| A | F | K | Q | V |
 |
This cartography or mapping term article is a stub. You can help Wikipedia by expanding it. |
 |
This standards- or measurement-related article is a stub. You can help Wikipedia by expanding it. |
