Definition

The following constraints apply to instances of <Feature Volume>/<Geometry Volume>, respectively:

1. A <Feature Volume> instance V shall have the following relationship with its associated <Feature Edge> instances, if any exist.

   1. At any feature topology level, if V is associated with any <Feature Edge> instance E, E shall lie completely within the external shell of V, if any, and shall not lie within any of the internal shells of V, if any.

   2. At feature topology levels 5 and higher, if a <Feature Edge> instance E lies within the boundaries of V, E shall be associated with V.

   3. At any feature topology level, if no <Feature Edge> instances lie within its boundaries, V shall not be associated with any <Feature Edge> instances.

2. A <Geometry Volume> instance V shall have the following relationship with its associated <Geometry Edge> instances, if any exist.

   1. At any geometry topology level, if V is associated with any <Geometry Edge> instance E, E shall lie completely within the interior of V.

   2. At geometry topology levels 5 and higher, if a <Geometry Edge> instance E lies completely within the interior of V, E shall be associated with V.

   3. At any geometry topology level, if no <Geometry Edge> instances lie completely within its interior, V shall not be associated with any <Geometry Edge> instances.

Rationale

The association between <Feature Edge> and <Feature Volume> implements a containment relationship. This topological relationship must be consistent, and must be consistent with the geometric representation of these objects.

The association between <Geometry Edge> and <Geometry Volume> implements a containment relationship. This topological relationship must be consistent, and must be consistent with the geometric counterparts of these objects.

Example

1. Consider a <Feature Edge> instance E1 that is "floating" within the interior of a <Feature Volume> instance V1. E1 is contained within V1, and V1 contains E1.

2. Consider a <Geometry Edge> instance E1 that is "floating" within the interior of a <Geometry Volume> instance V1. E1 is contained within V1, and V1 contains E1.

FAQs

If a <Feature Edge> instance is contained within the interior of a <Feature Volume> instance, must the <Feature Node> instances that bound that <Feature Edge> instance also be contained within the interior of that same <Feature Volume> instance?

No. The <Feature Node> instances that bound such a <Feature Edge> instance may be contained within the containing <Feature Volume> instance V, or may be contained within the interior of one of the <Feature Face> instances that bound V, or may even be one of the <Feature Node> instances that bound one of the <Feature Edge> instances that in turn bound one of the <Feature Face> instances that bound V.

If a <Geometry Edge> instance is contained within the interior of a <Geometry Volume> instance, must the <Geometry Node> instances that bound that <Geometry Edge> instance also be contained within the interior of that same <Geometry Volume> instance?

No. The <Geometry Node> instances that bound such a <Geometry Edge> instance may be contained within the containing <Geometry Volume> instance V, or may be contained within the interior of one of the <Geometry Face> instances that bound V, or may even be one of the <Geometry Node> instances that bound one of the <Geometry Edge> instances that in turn bound one of the <Geometry Face> instances that bound V.