3QXV41 indicates location to within 10,000m 3QXV4312 indicates location to within 1,000m 3QXV432123 indicates location to within 100m 3QXV43211234  indicates location to within 10m 3QXY4321012345    indicates location to within 1m 3-23  Non-Standard Grids a.  General.  Many grid systems were developed by individual nations which cover only that nation or a region surrounding that nation.  In most cases, no direct relationship exists between the local grid systems; the  same as no direct relationship exists between the state plane grid systems of the US states. Non-Standard grids are discussed in detail in DMA TM 8358.1. b.  Names.  Non-Standard grids are generally named for the nation or region they cover and will normally contain the term Grid, Zone, or Belt (i.e. Ceylon Belt, Madagascar Grid, and India Zone I).     1.  A Grid covers a relatively small area.  Its limits consist of combinations of meridians, parallels, rhumb lines, or grid lines.     2.  A Zone is usually wide in longitude and narrow in latitude.  Its limits consist of meridians and parallels.     3.  A Belt is usually wide in latitude and narrow in longitude. 3-24  World Geodetic Reference System     The World Geodetic Reference System (GEOREF) is an alphanumeric system for reporting positions based on geodetic coordinates.  It is a worldwide position reference system that can be used with any map or chart graduated in latitude and longitude, regardless of the map projection.  The primary use of the GEOREF is for inter-service and inter-allied positioning and reporting of aircraft and air targets.  This system is discussed in detail in DMA TM 8358.1.    3-25  User-Defined Grid Systems a.  When operating in an area which is mapped in a grid system other than UTM and UPS, it may become necessary to "define" the grid system.  Defining the grid system is basically orienting a fire support system or survey system to measure or establish azimuths, distances, and elevations from a different origin than it is programmed for.  Most current software versions do not allow this option; however, if the option is available, the following information is necessary:     Ellipsoid Parameters (a, b, f )     Scale Factor (at the origin) for the projection     Latitude of the origin     Longitude of the origin     Unit  (i.e. meters, feet, yards, chains, rods)     False easting of the origin     False northing of the origin b.  Figure 3-26 lists the needed information for several common non-standard grids as published in Table 6 of DMA TM 8358.1. c.  Figure 3-27 lists the needed information for several common non-standard grids not published in DMA TM 8358.1. DRAFT 3-25