Subject: Re: [Geopriv] Work on "geo-URI" style information in vcarddav

From: "Carl Reed" <[email-masked]>
Date: Mon, 6 Apr 2009 16:52:24 -0600

Alexander -

The concept of a very simple encoding for a 2d point is very useful. As you 
point out, in the wild such simple definitions lack the proper semantics and 
informative text to truly make the encoding truly useful (and 
interoperable). There have been similar discussions in the W3C, the OGC, the 
OpenSearch group, the GeoRSS community, and so on.

Beyond the proper expression of the coordinate reference system, there are 
some interesting semantics related to what is meant by a "point" or 
"coordinate". Not to seem too much a standards wonk, but from ISO TC 211 
19111 and 19107:

1. coordinate

one of a sequence of N-numbers designating the position of a point in 
N-dimensional space [ISO 19111]

2. point

0-dimensional geometric primitive, representing a position

3. geometric primitive

geometric object representing a single, connected, homogeneous element of 
space

NOTE Geometric primitives are non-decomposed objects that present 
information about geometric configuration. They include points, curves, 
surfaces, and solids.

and so on.

One has got to love the wonderful richness of the semantics of geospatial 
data!

That said, you are absolutely correct that the semantics need to be properly 
expressed and documented.

For other information on geo microformats, check out 
http://microformats.org/wiki/geo . Notice all the *card references.

Cheers

Carl

----- Original Message ----- 
From: "Alexander Mayrhofer" <[email-masked]>
To: <[email-masked]>
Sent: Thursday, March 26, 2009 2:23 AM
Subject: [Geopriv] Work on "geo-URI" style information in vcarddav

>
> I was attending vcarddav today, and one of the things they are currently
> contemplating is the extension of the "ADR" property in a vCard to also
> support a spatial coordinate pair, with a simple example looking like:
>
> ADR;GEO=46.772673,-71.282945:;;2600 boul.
> Laurier\, suite 625;Quebec;QC;G1V
> 4W1;Canada
>
> Ignoring the semantical problems of mixing spatial/civic addresses, this
> is yet another example where a simple compact representation of lat/lon
> coordintes seems to be useful. I mentioned my work on the "geo" URI, and
> over the course of the discussion, the following alternative example was
> posted to the mailing list:
>
> ADR;GEO="geo:48.2010,16.3695,183";PREF=1:XYZ;;;;;;
>
> Note that besides the addition of the URI scheme identifier (and the
> optional altitude in the example above), this is nearly identical to
> what the vcarddav group came up with. So, this would be another use case
> for the short, simple, but still semantically clear way to reference to
> a spatial location.
>
> I think that if we provide clear definition and semantics for such a
> "simple representation", it saves the developers of protocols / data
> formats a lot of time, and also reduces the risk that there is
> ambigiuity over the interpretation of fields (for example, some of those
> "simple" formats in the wild still don't clarify which reference system
> is supposed to be used). This would help in interobaility of such
> "simple" lat/lon information.
>
> I'd therefore like to ask the chairs and the WG to think whether
> adoption as an WG item would be useful - There has also been already
> some discussion regarding privacy parameters of the URI scheme - Alissa
> and John, maybe you could give your view on what you'd like to see in
> the URI scheme with regards to privacy? The vCard itself, for example,
> is very much a "possession" model - i'm not aware of any privacy
> indication in the vCard format as it is currently deployed..
>
> Alex
>
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