Up to now I thought the range of values in the geographic coordinate systems was:

Latitude (S-N):   -90 to  +90  
Longitude (W-E): -180 to +180

I have set the coordinate system of my ArcGIS data frame in an empty map to WGS 1984 and I'm getting numbers like the following when I move the mouse over the window:

enter image description here

What does it mean?

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    Insert a new dataframe, don't set the coordinate system, then add a world shapefile, select it then zoom to full extent and re-examine. I suspect the values are nonsense – user681 Sep 15 '13 at 16:14
  • so @DanPatterson as you say I need a world shapefile that has geographic coordinate system but I don't have one and also googling didn't help me to find such a file. So it would be appreciated if you introduce me a link to such file. – Sepideh Abadpour Sep 15 '13 at 16:32
  • If you are using ArcGIS, you should have access to their sample data or use data from ArcGIS online...other software should also have similar packaged data sets – user681 Sep 15 '13 at 17:35
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    check your installation CD's I am sure there were datasets there or go to www.esri.com or www.esricanada.com and see if they have teaching sets there. Also "world shapefile" ArcMap on Google produced many potential sources – user681 Sep 15 '13 at 17:57
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    First address for free earth data is naturalearthdata.com/downloads/110m-physical-vectors – AndreJ Sep 15 '13 at 18:15

Technically, since it's angular measurement, there is no limit to the longitude value (trig functions operate correctly outside of +/-2pi). It's conventional to use data sources with range [-180,180] or [0,360], but many software packages permit panning to the east or west of the data limit, and re-render the data, shifted in 360 degree increments. Values north of 90 or south of -90 are of course not valid, but so is "hovering" outside the data window (garbage in, garbage out).

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  • what do you mean by (garbage in, garbage out)? – Sepideh Abadpour Sep 15 '13 at 16:33
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    You can enter data as you like, but if you want to reproject the data to any useful projected coordinate system, the degrees should be within the usual limits. Some projections do not even like 90° North or South. – AndreJ Sep 15 '13 at 18:17

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