Abstract: A system for locating geographic points on maps, charts and the like uses a rectangular grid with sides tangent to the corresponding geographical extremities of the area (city, county, state, nation, etc.) represented on the chart. Two decimal scales extend from the zero ordinate of the grid, with unit ordinates at their opposite ends. Thus, a feature along either scale and therefore a line of position across the enclosed geographical area represented, may be defined by a decimal number between zero and one and the intersection of the lines of position representing a point on the represented area may be defined by a two decimal array. Tables of the decimal arrays for specific points may be provided, and the system is extendible to different maps and/or insets of dissimilar scale, so long as the decimal scales are consistently used between each map. The system may be further extended to provide point feature within three dimensional volumes by using a three decimal array.

Abstract: A system for locating geographic points on maps, charts and, the like uses a rectangular grid with sides tangent to the corresponding geographical extremities of the area (city, county, state, nation, etc.) represented on the chart. Two decimal scales extend from the zero ordinate of the grid, with unit ordinates at their opposite ends. Thus, a location along either scale and therefore a line of position across the enclosed geographical area represented, may be defined by a decimal number between zero and one and the intersection of the lines of position representing a point on the represented area may be defined by a two decimal array. Tables of the decimal arrays for specific points may be provided, and the system is extendible to different maps and/or insets of dissimilar scale, so long as the, decimal scales are consistently used between each map. The system may be further extended to provide point location within three dimensional volumes by using a three decimal array.