| Enumerant | Definition | Value |
|---|
| SE_FEAT_UNION_REASON_SHARED_ATTRIBUTE |
The <Feature> instances in the union all share one or more attribute
values, and have been grouped so that the attribute(s) can
be attached to the union rather than to each individual feature.
|
1 |
| SE_FEAT_UNION_REASON_COMPOUND |
The union represents a compound <Feature>, i.e., a <Feature> that
is made up of multiple <Feature Topology> instances, e.g. a <Linear
Feature> that is made up of multiple <Feature Edges>.
For example, SEDRIS requires that all of the <Feature Edges> that
make up a single <Linear Feature> be connected, but VPF doesn't,
so sometimes a VPF compound line feature shall be broken up in
order to be represented in SEDRIS. When this happens, all of the
resulting <Linear Feature> instances are placed in a <Union of Features>
marked with SE_FEAT_UNION_REASON_COMPOUND.
|
2 |
| SE_FEAT_UNION_REASON_COMPLEX |
The union represents a complex feature, i.e., a <Feature> that is
made up of multiple <Feature> instances. The classic example is an
airfield that is made up of runways, taxiways, control tower,
hangars, and so on.
|
3 |
| SE_FEAT_UNION_REASON_TILE_REFERENCE |
An <Areal Feature> that defines the spatial extent of a tile.
In SEDRIS terms, a tile is a branch of a <Spatial Index Related>
or <Perimeter Related> aggregation, such as a <Spatial Index
Related Feature Topology> or a <Perimeter Related Features>.)
Tile reference features can also show up as ordinary features;
when they do, they are collected in a union with this label.
|
4 |
| SE_FEAT_UNION_REASON_UNKNOWN |
If there was a reason for creating this union, the data provider
either doesn't know what it was or isn't saying.
|
5 |