[Ietf-calsify] GEO in draft-ietf-calsify-rfc2445bis-07.txt

[Steve Allen]

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

ITRF
http://itrf.ensg.ign.fr/

WGS-84 is defined for the US GPS system
http://en.wikipedia.org/wiki/WGS84

ETRS is a product of EUREF
http://lareg.ensg.ign.fr/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