[Ietf-calsify] GEO in draft-ietf-calsify-rfc2445bis-07.txt
mrdemeanour at jackpot.uk.net
Tue Jul 10 10:46:03 PDT 2007
Eliot Lear wrote:
> Thanks for your comment. Can you restate your point in a succinct
> proposed textual change?
If I read it correctly, it doesn't call for a textual change. It's
simply pointing out that six decimal places/one meter may be spurious
precision (one could add prose to that effect, of course).
> Steve Allen wrote:
>> In the context of metrology I wonder about the text in 188.8.131.52.
>> Geographic Position
>> It says The longitude and latitude values MAY be specified up to
>> six decimal places, which will allow for accuracy to within one
>> meter of geographical position.
>> This is only true if the geodetic datum is specified.
>> I point out the US DoD's instructional page to soldiers on this
>> At a more technical level I point out the partial list of datums in
>> use at
>> where in the links to the graphics for table 2 it is immediately
>> evident that some older geodetic datums upon which available maps
>> are based differ by hundreds of meters from the more recent,
>> satellite-geodesy-based datums.
>> In much the same vein as quoting the standards documents for UTC,
>> if the values used in this field are to be believed at a level of 1
>> meter, then it is at the least necessary to require that the
>> latitude and longitude values be expressed in a standard geodetic
>> datum created no earlier than the year 1980.
>> -- Steve Allen <sla at ucolick.org>
>> WGS-84 (GPS) UCO/Lick Observatory Natural Sciences II, Room
>> 165 Lat +36.99855 University of California Voice: +1 831 459
>> 3046 Lng -122.06015 Santa Cruz, CA 95064
>> http://www.ucolick.org/~sla/ Hgt +250 m
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