| Enumerant | Definition | Value |
|---|
| SE_FEAT_TOPO_LVL_ZERO |
Topology level 0.
The following objects and relationships are required to exist:
Objects:
<Feature Node>
Unless the data consists solely of isolated (i.e., entity)
<Feature Node> instances, the following objects (and the
relationships among them) are all required to exist:
- <Feature Edge>
- <Connected Feature Edge>
Other types of feature topology objects and relationships MAY
exist at level 0, but the requirements of level 1 are NOT met.
|
1 |
| SE_FEAT_TOPO_LVL_ONE |
Topology level 1.
No objects or relationships other than those present for level
0 topology are required. However, each <Feature Node> shall have
unique <Location> coordinates (i.e., two or more <Feature Node>
instances cannot be colocated).
|
2 |
| SE_FEAT_TOPO_LVL_TWO |
Topology level 2.
No objects or relationships other than those present for level
1 topology are required. However, <Feature Edge> instances may
not intersect or overlap one another, except where they meet at
a common <Feature Node>.
|
3 |
| SE_FEAT_TOPO_LVL_THREE |
Topology level 3.
The following objects and relationships are required to exist, in
addition to the requirements of topology level 2:
Objects:
<External Feature Face Ring>
<Internal Feature Face Ring>
<Regular Feature Face>
<Universal Feature Face>
Relationships:
1. The set of <Regular Feature Face> instances shall be exclusive
and exhaustive, forming a complete surface (i.e.,
<Regular Feature Face> instances may not intersect or overlap
one another, except where they meet at a common <Feature Edge>.
2. Exactly 2 <Feature Face> instances border each <Feature Edge>.
Consequently, all <Feature Edge> instances shall have an
association to at least one <Feature Face>.
3. Each <Feature Face> shall have an association to each
<Feature Node> within its boundaries, and each
<Feature Node> shall have an association with every
<Feature Face> that contains it.
|
4 |
| SE_FEAT_TOPO_LVL_FOUR |
Topology level 4.
The following objects and relationships are required to exist, in
addition to the requirements of topology level 3:
-- <Location 3Ds> are required.
-- There shall be at least one case where more than 2 <Feature Face>
instances meet at a single <Feature Edge>.
<Feature Edge> instances are no longer required to bound
<Feature Face> instances. If a <Feature Edge> does bound a
<Feature Face>, the <Feature Edge> shall have an association
to that <Feature Face>.
|
5 |