Looking for a way to attach geographical metadata to my pictures, I have found out about 3 efforts to try to bind the data available on the internet into a new layer searchable by location. If I am looking for infos on Tokyo, I would find posts, articles or pics that are dealing with Tokyo and posted from anywhere (and not data posted from Tokyo regarding somewhere else).
1- The Dublin Core Metadata Initiative (DCMI) advocates the use of the Getty Thesaurus of Geographic Names (TGN).
2- Andrew Daviel proposes his Geo Tags for HTML headers.
3- The Open Gis Consortium develops geoprocessing specifications known as Geography Markup Language (GML).

And for those who still don't get it, Headmap will settle it.

So which one should I go for?