recognize that all you can do is discard the information received.
I'm not clear how useful all the different CRSes are going to be in
practice, given that the producer of the URI will generally have no
idea as to who will read it and there's no way to negotiate
capabilities if the URL is on a web page. There are only three choices
in an open environment:
(1) Either the sender re-codes the datum to WGS-84, if that is
possible without losing information;
(2) Or it negotiates what datum to use, hoping to find common ground -
only applies in certain circumstances and would point to extensions
of, say, HTTP;
(3) Or it provides multiple versions, in the hope that one of them
will work for the receiver.
Closed communities obviously don't have this problem, since everybody
can be assumed to "speak" a certain CRS.
I'm unclear what model is being anticipated here. Without it, we have
designed a mechanism that can reliably discard bits, but no
interoperability.
Henning
On Sep 2, 2009, at 5:37 PM, Andy Mabbett wrote:
> In message <8BC845943058D844ABFC73D2220D4665088A0634@nics-mail.sbg.nic.at
> >, Alexander Mayrhofer <alexander.mayrhofer@nic.at> writes
>
>> A nice metaphor just came to my mind:
>>
>> My native language is German, while your's is probably Russian
>> (wild guess!). Still, we are using English to converse with each
>> other - because it gives us interopability, and in the end allows
>> us to communicate with each other. The other option would be than
>> everybody learns all the 200 (wild guess again!) languages that are
>> spoken in the world - just in case we *might* need one of those one
>> day. That would be a lot of effort if everybody would learn every
>> possible language "just for the case".
>
> That's not a metaphor, it's an analogy; and it's extensible, in that
> we have "lang" attributes in HTML and other systems, so that the
> language (= CRS) in use can be specified.
>
> --
> Andy Mabbett
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> Geopriv@ietf.org
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