[APG Public List] place names

Terry Reigel terry at reigelridge.com
Wed Oct 27 09:44:22 MDT 2010

Stephen Danko wrote:
> GPS coordinates can be specified so that they represent
> either a large general area or a spot the size of a
> pinpoint.  It's all in how many significant figures one
> lists in the coordinates.

Your point makes perfect logical sense, Stephen. But to me the issue is how to get those reading those coordinates to understand the difference between high and low precision figures? If a reader plugs the coordinates into an a mapping service or application, as far as I know, there is no difference in result between high and low precision data. A very precise spot is identified, even though the actual coordinates may be very un-precise.

So if one uses coordinates to define a general area it falls upon the writer to communicate to the reader that the coordinates are approximate, or represent the center or an area, etc., as the case may be. It seems to me that to rely on including fewer significant digits alone risks misleading the reader.

Stephen wrote in a later message:

> ... So, how do we cite sources for these coordinates? 
> Should the precision of the measurement be specified in
> the source, in the coordinate itself, or in a note?  The
> fields for coordinates in Family Tree Maker 2011 include
> no provision for recording precision and, as far as I can
> tell, include no provision for recording a source
> citation or a note for the coordinates.

I'm not familiar with other programs, but in TMG the coordinates field is just one of several place fields, all of which can be cited along with the other fields. So a user can include a citation to the source of the coordinates, and mention in the Citation Detail any note about the precision of the measurement, and/or in the case of larger areas, how the coordinates relate to the area being described.

One may be able include some indication (other then fewer significant digits) in the data field, if the program doesn't preclude that by editing the values entered. But doing so is likely to disable automatic plotting features that may be depending on that data. For example, TMG will let you include any text you like in the coordinates field (after warning you that the data is not in an expected format) but doing so will likely cause both TMG's own mapping feature and that of the companion website-building program Second Site to fail.

Terry Reigel

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