letter is columnar, it is the same for all squares in a north-south column.  The second letter is linear, it is the same for all squares in an east-west row in a grid zone.  See Figure 3-24.  This identifier is usually listed as part of the marginal information on a military map. The lettering convention used is dependent on the reference ellipsoid.  This text will discuss the UTM lettering convention used with the WGS84/GRS80 ellipsoid and the UPS lettering convention used with the International ellipsoid.  Other ellipsoid lettering conventions are detailed in DMA TM 8358.1.     1.  UTM. a.  The first (columnar) letter of the 100,000 meter square identification originates at the 180° meridian with the letter A and increases alphabetically eastward along the equator for three grid zones to cover an area of 18°.  The 100,000 meter columns, including partial columns at grid zone junctions, are lettered from A to Z omitting I and O.  This alphabet is repeated every 18° eastward around the earth. b.  The second (linear) letter of the 100,000 meter square identification is lettered from A to V, omitting I and O, from south to north covering an area of 2,000,000 meters and is then repeated northward. In odd numbered grid zones, it originates at the equator increasing alphabetically north.  In even numbered grid zones, the second letter originates 500,000 meters south of the equator increasing alphabetically north.  Therefore, in odd numbered grid zones, the second letter of the 100,000 meter square identification is A along the equator; in even numbered grid zones the second letter is F along the equator. c.  Referencing Figure 3-24, you can see that each 6° by 8° square is broken up into 100,000 meter squares which occur only once.  For example, there is only one square identified by the letters WA inside of the 6° x 8° square of grid zone designation 3N.  The only other square in this figure identified by the letters WA is in grid zone designation 3Q.  It can be seen from this example that unique coordinates can be established for every position within the UTM grid using the MGRS.              2. UPS.  The 100,000 meter square identifiers are the same for both UPS grid zones.  The difference between two UPS grid MGRS coordinates with the same 100,000 meter square identifiers is the grid zone designator; A/B in the south, Y/Z in the north. Designators A and Y (western hemisphere) are lettered the same, as are designators B and Z (eastern hemisphere).  It must be understood; however, that the north zone only includes that portion of the lettering convention which falls inside of 84° latitude.  See Figure 3-25. a.  Western Hemisphere.  The first letter of the 100,000 meter square identifier originates at the intersection of the 80° latitude and 90° W longitude lines.  It is lettered alphabetically along the east-west axis from J to Z with M, N, O, V, and W omitted.   b.  Eastern Hemisphere.  The first letter of the 100,000 meter square identifier originates at the 0° and 180° meridians.  It is lettered alphabetically along the east-west axis from A to R with D, E, I, M, N and O omitted. c.  The second letter of the 100,000 meter square identifier originates at the intersection of the 80° latitude/ 180° longitude lines.  It is lettered alphabetically from A to Z with I and O omitted. d.  MGRS Grid Coordinates.     1.  The easting and northing coordinates used with the MGRS are the same as the grid coordinates used with UTM/UPS with the following modifications: a.  For UTM grid MGRS coordinates, delete the first digit (100,000 meters) from the easting and the first two digits (1,100,000 meters) from the northing of the UTM grid coordinates.  Add the grid zone number, the zone designator, and the 100,000 meter square identifier at the front of the coordinates. b.  For UPS grid MGRS coordinates, delete the first two digits (1,100,000 meters) from both the easting and northing UPS grid coordinates.  Add the zone designator and the 100,000 meter square identifier at the front of the coordinates.     2.  The entire MGRS grid coordinate is written as one entity without parenthesis, dashes, or decimals. Examples: 3Q indicates location within a 6° x 8° square 3QXV indicates location to within 100,000m DRAFT 3-37