Standardized CAD Application Relationships
This section describes the components necessary for the mapping of CAD external relationships in Windchill. While many categories of external relationship are defined, not all are used by every application, as not all CAD applications provide access to detailed reference information:
• Design Reference—The design external reference is a general category of external reference used in two situations:
◦ When your CAD application generates external reference information which is not granular enough to map to a specific category of reference.
◦ When data is upgraded from Windchill 8.0 for non-Pro/ENGINEER or Creo CAD applications. On the first checkin to Windchill 9.0, external references are updated to the Windchill 9.0 categories.
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"Upgrade" is not mere migration. It refers to the situation where, during or after migration, additional categorization of external reference information is captured in data files.
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• Relation Reference—Relational references are generally not required references. They are created when two items are linked together by sharing a physical reference, or by an equation that links the two items. The reference is used by the target, but is not copied to the target. Relation references point to the context in which the relationship was created (for example, an assembly or layout). For example:
◦ Create an up-to-surface protrusion or using holes in one part to position holes in a mating part
◦ Write expressions to drive model A, using model B; or use physical references in the one part to drive a feature in another part
• Derived Reference—Derived references are created when elements of one model are copied to another model. The copied reference may be anything from a curve to the geometry an entire model. The copied reference relationship is only created if the user chooses to create a dependent copy (if they have the choice). The geometry added to the target can have new geometry added to it. In general, the copied features themselves cannot be edited. Derivation references feature single direction associativity. A change in the source item propagates to the target item in the context in which the copy was created (for example, an assembly). From a reference link perspective, derived references point from the target item to the source item for the copy. The reference may or may not be required; it depends on the nature of the CAD application. For example:
◦ Copying a part into a new part. This situation can be treated differently by different CAD applications.
