[Ietf-calsify] GEO in draft-ietf-calsify-rfc2445bis-07.txt
sla at ucolick.org
Tue Jul 10 11:12:08 PDT 2007
On Tue 2007-07-10T19:38:03 +0200, Eliot Lear hath writ:
> Can you restate your point in a succinct
> proposed textual change?
Not for sure. As written I don't know what it means nor how I would
come to agreement with other parties about what it means.
If I give you my latitude and longitude based on the USGS topo
maps on my wall it will be off by 100 meters from the WGS-84
coordinates in my .sig.
I'm not sure how exactly GEO is intended to be used, by machines
or humans, and I'm at a loss to reconcile the historical gotchas
other than by adding several sentences.
In the absence of further input about how this is expected to be used
I suppose I would suggest something like this:
The latitude and longitude MAY be expressed in any geodetic datum, but
if the application demands 1 meter precision then the parties
exchanging the information MUST agree on a particular datum. In the
absence of agreement the coordinates SHOULD be interpreted as any one
of ITRF, WGS-84, ETRF, or some other post-1980 satellite-based
geodetic datum (all of which agree at the level of 1 m).
Here are some refs
WGS-84 is defined for the US GPS system
ETRS is a product of EUREF
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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