Temporal Object Types
| Object Type | Description | Example Phenomena |
|---|---|---|
| TM_Instant | Point in time with no extent | Measurement registration |
| TM_Period | Period of time with start and end instant | Building construction time |
| MultiInstant | Composition of TM_Instant's | Case of cholera is diagnosed at a buildung |
| MultiPeriod | Composition of TM_Period's | Forest fires within the same forestral area |
| MultiRegularInstant | Instants that occure regularly | Recording instants of an automatic webcam |
| MultiRegularPeriod | Periods that occure regularly | Weekly fruit-market |
The temporal objects, dedicated to abstract time information include six classes. Two are defined by ISO19108 in a detailed way as TM_GeometricPrimitives: TM_Instant and TM_Period. These classes conduce to the modeling of points or intervals in time. Two additional classes are nothing more than compositions of one kind of the primitive objects. If a feature is in congruent states at multiple times this can be represented with a MultiInstant or MultiPeriod. Some phenomena eventually repeat their validity regularly in the time dimension. To meet these requirements, the last two classes are conceived: RegularMultiInstant and RegularMultiPeriod. All these six mentioned classes are based on the contents of ISO19108, even if the temporal complexes are not described in detail in the standard. They serve for the modeling of feature characteristics in the temporal domain by representing the so called geometry of time. There are no additional semantics linked to the objects because it is believed that questions like if an object represents an event or a state should be answered within an application schema. Examples for the different classes are listed in the table above. The attribution of the examples to the objects cannot be seen as strictly unambiguous because the same phenomena can be modeled in different ways, depending on the issue.