Hello Rick:

The notation used to describe the X-Y co-ordinates of a location has no impact on the accuracy of the description of the location, other than the obvious, which is that the more significant digits there are, the more accurate the location will be.

Let me try to explain that a bit better:

Paris, France has a large tower designed by Eiffel in the middle of the city. We can note (notate?) the co-ordinates of that tower in a number of different ways, such as -

48.85837, 2.294481 This is how most GPS devices and most GIS (Geographic Information Systems) store and define the location. It is decimal, with 48 being the latitude and 2 being the longitude. The latitude is north and the longitude is east. South latitude and west longitude would be preceded by a minus sign.

Regardless of how you have configured your GPS device to display lat/long to you, this is most likely how the device stores waypoints within it.

N48° 51' 30.132" E2° 17' 40.1316" This is the same location, expressed in degrees-minutes-seconds. The level of precision is the same, because the number of significant digits is the same.

It is noteworthy that even though the above notation is degrees-minutes-seconds, a decimal value (fraction of a second) is appended to the seconds in order to achieve the same degree of precision as the first example.

If the decimal fraction of a second was not appended, the result would be N48° 51' 30 E2° 17' 40, which doesn't have the same level of precision only because it has fewer significant digits.

There are many other ways of noting a location - UTM notation is commonly used by military forces (including Search and Rescue), and UTM is an entirely different way of describing a location.

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The best analogy I can think of is to compare normal decimal numbers that we use in everyday life with Roman Numerals or hexadecimal notation. We can write the current year as 2014, or as MMXIV, or as (838)[sub]16[/sub]. It's all the same thing, and all three values have the same level of precision (only to the 'year' level, not to the day or month of the year).

Hope this helps,

Michael

PS: In the last paragraph above, the '16' after 838 should appear as a subscript, to indicate that it is base 16 notation. But this forum does not support the UBB code for a subscript, which is why you see the formatting code 'sub' before and after the number 838.