BP5: suggestion

Best Practice 5: Describe the positional accuracy of spatial data

Says under "Why?" ---" the precision of the specified coordinates, the accuracy of positioning on the actual earth's surface using WGS84 will only approach about a meter horizontally and may have apparent errors of up to 100 meters vertically, because of assumptions about reference systems, tectonic plate movements and which definition of the earth's 'surface' is used."

That's fair enough, but does not seem to be an answer to why?. Suggest move this down a bit  and for "why " say something like:


"Some spatial data applications , such as aircraft  navigation , [more?] require highly accurate data. If the positional accuracy is published together with the data, the user can determine whether it is appropriate to use for an application. Potentially, this makes existing data more re-usable.


Kerry