is (normally) a 6° × 8° polygon called a grid zone, whose designation in MGRS is formed by the zone number (one or two digits – the number for zones 1 to 9 is just a single digit, according to the example in DMA TM 8358.1, Section 3-2, Figure 7), followed by the latitude band letter (uppercase). 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. As Figure 1 illustrates, Honolulu is in grid zone 4Q. 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. 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. If an MGRS coordinate is complete (with both a grid zone designation and a 100,000 meter square identification), and is valid in one lettering scheme, then it is usually invalid in the other scheme, which will have no such 100,000 meter square in the grid zone. (Latitude band X is the exception to