Definition

<Feature Face> instances have the following relationship with <Feature Volume> instances. At any topology level, if a <Feature Face> FF associates to a <Feature Volume> FV, then FV shall have a component <Feature Volume Shell> that associates to FF. Conversely, if a <Feature Volume> FV has a <Feature Volume Shell> that associates to a <Feature Face> FF, then FF shall also associate to FV.

<Geometry Face>s have the following relationship with <Geometry Volume>s. At any topology level, if a <Geometry Face> GF associates to a <Geometry Volume> GV, then GV shall also associate to GF. Conversely, if a <Geometry Volume> GV associates to a <Geometry Face> GF, then GF shall also associate to GV.

Rationale

The associations between <Feature Face> and <Feature Volume> implement a boundary/co-boundary relationship. This topological relationship must be consistent, and must be consistent with the geometric representation of these objects.

The associations between <Geometry Face> and <Geometry Volume> implement a boundary/co-boundary relationship. A <Geometry Volume> is bounded by one or more <Geometry Face>s. This topological relationship must be consistent, and must also be consistent with the geometric counterparts of these objects.

Example

1. A <Feature Volume> V1 representing a cube is bounded by six <Feature Face> instances F1 through F6. V1 is associated to F1, F2, F3, F4, F5, and F6 via its exterior <Feature Volume Shell>. Also, F1, F2, F3, F4, F5, and F6 are all associated to V1.
2. A <Geometry Volume> V1 representing a cube is bounded by six <Geometry Face>s F1 through F6. V1 is associated to F1, F2, F3, F4, F5, and F6. Also, F1, F2, F3, F4, F5, and F6 are all associated to V1.

FAQs

Can a <Feature Face> instance be associated with a <Feature Volume> more than once?

Yes. A <Feature Face> that "dangles" into the interior of a <Feature Volume> will appear twice in the collection of <Feature Face> instances that are associated with the exterior <Feature Volume Shell> of that <Feature Volume>, once with each orientation.

Can a <Geometry Face> be associated with a <Geometry Volume> more than once?

Yes. A <Geometry Face> that "dangles" into the interior of a <Geometry Volume> will appear twice in the collection of <Geometry Face>s that are associated with that <Geometry Volume>, once with each orientation.