# description
The extent of the collection. In the Core only spatial and temporal extents are specified. Extensions may add additional members to represent other  extents, for example, thermal or pressure ranges.
It is recommended that the statial extent is expected in CRS84 except if this is not possible.

# properties.temporal.description
The temporal extent of the element in the collection.

# properties.temporal.properties.interval.description
One or more time intervals that describe the temporal extent of the dataset.
The value `null` is supported and indicates an open time intervall.
In the Core only a single time interval is supported. Extensions may support
multiple intervals. If multiple intervals are provided, the union of the
intervals describes the temporal extent.

# properties.temporal.properties.interval.items.description
Begin and end times of the time interval. The timestamps
are in the coordinate reference system specified in `trs`. By default
this is the Gregorian calendar.

# properties.temporal.properties.trs.description
Coordinate reference system of the coordinates in the temporal extent
(property `interval`). The default reference system is the Gregorian calendar.
In the Core this is the only supported temporal reference system.
Extensions may support additional temporal reference systems and add
additional enum values.