the fact that the anthill is hidden under the ground (it is an "estimated object"), or the formal definition of its delimitation, etc. This kind of uncertainty has no correlation with the location (e.g. GPS) uncertainty measure. the disk representing the anthill (as uncertainty of the object) is modeled as 2σ to be a 95% of confidence area. the point is a GPS location measure, that is, the "center" of the projection of the 3D object in the 2D surface. The total uncertainty is the sum of GPS error and object-definition error. The latitude and longitude GPS errors need to be simplified (to a disk) and converted into meters. If the errors were inferred from a different model, they need to be converted to the Gaussian model. Unofficial extensions Some vendors, such as Android OS, have adopted extensions to the "geo" URI scheme: z: Zoom level for Web Mercator projection scaling. The value is an integer from 1 to 21. q: Perform a search for the keyword given around the point. If the location is given as "0,0", search around the current position. A parenthetical can be used to indicate the label to show on the map. Android adopts an unconventional approach to parsing the points: it does not show a map pin at the point given normally, and a map pin will show up only when given as the query. In other words, to show a pin at the Wikimedia Foundation office, one should not use geo:37.78918,-122.40335 but geo:0,0?q=37.78918,-122.40335. See also LOC record References External links RFC5870 Geo URI website Internet protocols Geocodes Geographic information systems URI schemes