[georss] Atom proposal

[Sean Gillies]

Let's get this ball rolling:

http://georss.org/proposals/atom-ground-state

Initial text below. I'm thinking that linked location might be an "n>1"
feature, but worth considering.

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Proposal:

Location for Atom Syndication

Abstract:

This document specifies the minimal, fundamental representation of
spatial location within Atom [1] feeds and entries.

Introduction:

Joshua Lieberman suggested "Ground State for Atom" as a name for this
work. "Ground" resonates well with "geography", but the original German
"grund", means fundamental -- and this proposal aims to be a
fundamental, minimal specification for location in Atom, relying on, and
being consistent with, other Atom and AtomPub extensions [2,3] wherever
possible, with the minimum of invention. Think "n=1".

Namespaces:

georss: http://www.georss.org/georss
gml: http://www.opengis.net/gml

The "georss:where" element:

The "georss:where" element conveys spatial location for an entry or
feed. To Atom, it is a structured extension element [4]. The element
contains a GML "simple features profile" geometry [5].

Cardinality: An Atom entry or feed may have 0-1 "georss:where" elements.

Relationship to GeoRSS 1.0:

GeoRSS 1.0 elements "elev", "radius" (obviated by use of GML), "floor",
"featurename", and "featuretypetag" (level n>1 features) are omitted.

References:

[1] Atom Syndication Format: http://tools.ietf.org/html/rfc4287
[2] Atom Threading Extension: http://tools.ietf.org/html/rfc4685
[3] Atom License Extension: http://tools.ietf.org/html/rfc4946
[4] Structured Extension Elements:
http://tools.ietf.org/html/rfc4287#section-6.4.2
[5] GMLSF: http://portal.opengeospatial.org/files/?artifact_id=15201