1. Military Grid Reference System

4. MGRS
The military grid reference system (MGRS) is the geocoordinate standard used by NATO militaries for locating points on the earth.
The MGRS is derived from the Universal Transverse Mercator (UTM) grid system and the universal polar stereographic (UPS) grid system, but uses a different labeling convention.
The MGRS is used for the entire earth.

5. An example of an MGRS coordinate, or grid reference, would be 4QFJ , which consists of three parts:
4Q (grid zone designator, GZD)
FJ (the 100,000-meter square identifier)
(numerical location; easting is 1234 and northing is 5678, in this case specifying a location with 10 m resolution)
An MGRS grid reference is a point reference system.

6. When the term 'grid square' is used, it can refer to a square with a side length of 10 km (6 mi), 1 km, 100 m (328 ft), 10 m or 1 m, depending on the precision of the coordinates provided. (In some cases, squares adjacent to a Grid Zone Junction (GZJ) are clipped, so polygon is a better descriptor of these areas.)
The number of digits in the numerical location must be even: 0, 2, 4, 6, 8 or 10, depending on the desired precision.
When changing precision levels, it is important to truncate rather than round the easting and northing values to ensure the more precise polygon will remain within the boundaries of the less precise polygon.

7. In instances where the polygon is not a square and has been clipped by a grid zone junction, the polygon keeps the label of the southwest corner as if it had not been clipped.
4Q GZD only, precision level 6° × 8° (in most cases)
4QFJ GZD and 100 km Grid Square ID, precision level 100 km
4QFJ precision level 10 km
4QFJ precision level 1 km
4QFJ precision level 100 m
4QFJ precision level 10 m
4QFJ precision level 1 m

9. Grid zone designation
The first part of an MGRS coordinate is the grid-zone designation.
The 6° wide UTM zones, numbered 1–60, are intersected by latitude bands that are normally 8° high, lettered C–X (omitting I and O).
The northmost latitude band, X, is 12° high.
The intersection of a UTM zone and a latitude band is (normally) a 6° × 8° polygon called a grid zone, whose designation in MGRS is formed by the zone number followed by the latitude band letter (uppercase).

10. This same notation is used in both UTM and MGRS, i. e
This same notation is used in both UTM and MGRS, i.e. the UTM grid reference system; the article on Universal Transverse Mercator shows many maps of these grid zones, including the irregularities for Svalbard and southwest Norway.
Figure 1. The origin of the MGRS grid, in the Pacific. Honolulu is in 4QFJ.

11. 100,000-meter square identification
The second part of an MGRS coordinate is the 100,000-meter square identification.
Each UTM zone is divided into 100,000 meter squares, so that their corners have UTM-coordinates that are multiples of 100,000 meters.
The identification consists of a column letter (A–Z, omitting I and O) followed by a row letter (A–V, omitting I and O).
Near the equator, the columns of UTM zone 1 have the letters A–H, the columns of UTM zone 2 have the letters J–R (omitting O), and the columns of UTM zone 3 have the letters S–Z.

12. At zone 4, the column letters start over from A, and so on around the world.
For the row letters, there are actually two alternative lettering schemes within MGRS:
In the AA scheme, also known as MGRS-New, which is used for WGS84 and some other modern geodetic datums, the letter for the first row – just north of the equator – is A in odd-numbered zones, and F in even-numbered zones, as shown in figure 1.
Note that the westmost square in this row, in zone 1, has identification AA.
In the alternative AL scheme, also known as MGRS-Old, which is used for some older geodetic datums, the row letters are shifted 10 steps in the alphabet.
This means that the letter for the first row is L in odd-numbered zones and R in even-numbered zones.
The westmost square in the first row, in zone 1, has identification AL.

13. In the map (figure 1), which uses the AA scheme, we see that Honolulu is in grid zone 4Q, and square FJ.
To give the position of Honolulu with 100 km resolution, we write 4QFJ.
Figure 2. The MGRS grid around Hawaii. Honolulu is in the 10 km square that is called 4QFJ15.

14. Numerical location
The third part of an MGRS coordinate is the numerical location within a 100,000 meter square, given as n+ n digits, where n is 1, 2, 3, 4, or 5.
If digits is used, the first 5 digits give the easting in meters, measured from the left edge of the square, and the last 5 digits give the northing in meters, measured from the bottom edge of the square.
The resolution in this case is 1 meter, so the MGRS coordinate would represent a 1-meter square, where the easting and northing are measured to its southwest corner.

15. If a resolution of 10 meters is enough, the final digit of the easting and northing can be dropped, so that only digits are used, representing a 10-meter square.
If a 100-meter resolution is enough, digits suffice; if a 1 km resolution is enough, digits suffice; if 10 km resolution is enough, digits suffice.
10 meter resolution (4 + 4 digits) is sufficient for many purposes, and is the NATO standard for specifying coordinates.

16. One always reads map coordinates from west to east first (easting), then from south to north (northing).
Common mnemonics include "in the house, up the stairs", "left-to-right, bottom-to-top" and "Read Right Up".

20. Polar regions Figure 3. The MGRS grid around the South Pole.
Figure 4. The MGRS grid around the North Pole.

21. THANKS…