<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META content="text/html; charset=US-ASCII" http-equiv=Content-Type> <META name=GENERATOR content="MSHTML 8.00.6001.18975"></HEAD> <BODY style="FONT-FAMILY: Arial; COLOR: #000000; FONT-SIZE: 10pt" id=role_body bottomMargin=7 leftMargin=7 rightMargin=7 topMargin=7><FONT id=role_document color=#000000 size=2 face=Arial> <DIV>For all the reasons offered earlier in this and the preceding threads "Digital Locations" and "place names," I agree that numerical reference systems are a useful way to describe the location of a geographic feature independent of changing boundaries and landscapes. As such, it is an item of information (evidence, when relevant to an issue) that needs a citation to its source--a sextant reading, GPS instrument, map measurement, GoogleMaps solution, or an original source cited elsewhere.</DIV> <DIV> <DIV> </DIV> <DIV>I do have a problem with "digital location" as an alternative to "GPS location". "Digital location," like the more descriptive "geodetic location," is a generic term applicable to different numerical reference systems for precisely designating points on the ground. Besides GPS (which is not a rectangular grid, and as noted earlier, differs slightly from latitude and longitude measured from the traditional meridian through the Greenwich Observatory, being based on a line 5.31 seconds of arc to the east, or 102.5 meters at the latitude of the observatory),  there are a number of other digital systems for designating geographic locations by numerical reference to a rectangular grid on a projected flat surface, known as plane coordinate systems. The most common is the UTM or Universal Transverse Mercator grid, with locations designated by distance in meters on x and y axes from an origin point in each of its 18 east-west zones. Other systems, commonly use in land surveying, are the older legally-adopted state plane coordinate systems, with locations designated in feet north and east from the origin of each state's grid.</DIV> <DIV> </DIV> <DIV>Note that the GPS designates a location on the most recent calculation of the earth's spheroidal surface in relation to its axis and equator. A GPS designation as a reference to a particular land location is subject to change as the continental plates shift with tectonic drift. The precision of the GPS system will now allow these changes to be observed and measured over the years (and the aiming points for intercontinental missiles adjusted accordingly).</DIV> <DIV> </DIV> <DIV>Donn <DIV> </DIV> <DIV><FONT lang=0 size=2 face=Arial FAMILY="SANSSERIF" PTSIZE="10">Donn Devine, CG, CGL<BR>Wilmington DE <BR><BR>CG, Certified Genealogist, CGL, and Certified Genealogical Lecturer are service marks of the Board for Certification of Genealogists, used under license by board certificants after periodic evaluation, and the board name is registered in the US Patent & Trademark Office.</FONT></DIV></DIV></DIV></FONT></BODY></HTML>