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Mobile Location Services: The Definitive Guide by Andrew Jagoe

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3. The Conceptual Framework

3.1. Features and properties

GML is an XML encoding for geographic features. In order to correctly interpret a GML document it is necessary to understand the conceptual model that underlies GML, which is described in the OGC Abstract Specification.

3.1.1. Object Model

A geographic feature is essentially a named list of properties. Some or all of these properties may be geospatial, describing the position and shape of the feature. Each feature has a type, which is equivalent to a class in object modeling terminology, such that the class-definition prescribes the named properties that a particular feature of that type is required to have. So a Road might be defined to have a name, a surface-construction, a destination, ...

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