Database Reference
In-Depth Information
of knowing. The problem is that these are statements that should really apply to the
name, not the place. The way to get around this is to treat the name as a resource,
not just a string value. This means we give it its own URI and can then say as much
about it as we like. For example, we can state the following:
Ash Fleet Farm has place name
Ash Fleet Farm (name).
2
mm:/181113 mm:hasPlacename mm:/n200.
mm:/n200 mm:text “Ash Down Farm”.
mm:/n200 mm:firstUsed 1891.
mm:/n200 mm:supersedes mm:/n305.
Ash Fleet Farm (name) text
“Ash Fleet Farm”.
Ash Fleet Farm (name) first
used 1891.
Ash Fleet Farm (name)
supersedes Manor Farm (name).
Here we are saying that Ash Fleet Farm has a name, and that the name itself is
important, and we can say things about it in its own right. This system is more com-
plicated than just treating the name as a value associated with the place, but we trade
off complexity for additional expressivity. One loss is that it is no longer possible
to associate the naming mechanism with the widely used
foaf:name
as it is too
simple an implementation. An advantage for some people is that the name is more
important, or at least as important, as the thing it is naming. People who need this
kind of use case typically might work for heritage organizations for which the name
is of significant historic interest. So, treating the name as a thing in its own right and
assigning it a URI not only enables Merea Maps to be more expressive, but also helps
its sister government agency Merea Heritage.
Names are therefore not always as simple as we would like them to be, and we
have to be careful when representing them as Linked Data. On one hand, we do not
want to make things too complicated, but on the other we want to make sure we can
represent them properly and at a level that is appropriate for our end users.
6.4 GEOMETRY
We have seen previously that geometry is a very important attribute of geographic
objects, and that in vector terms they are typically represented as points, lines, and
polygons. The simplest case is where a feature is represented by a single point. This
is certainly as simple as it gets, but even here choices exist concerning the projec-
tion system used. WGS86 is the most commonly used encoding of geometry on the
Web, which expresses the latitude and longitude of a feature, using two properties
Lat and Long. So, we could say that the Lat/Long of a representative point for Ash
Fleet Farm could be
Ash Fleet Farm Lat 45.19964.
mm:/181113 Lat 45.19964.
Ash Fleet Farm Long 5.65749.
mm:/181113 Long 5.65749.
Other coordinate systems can be applied by using alternate or additional proper-
ties. For example, Merea has a local grid system and tends to publish data with both
the local X,Y grid and Lat/Long.
