What occurs when you open a part with interpart expressions but the source part is not loaded?

When opening a part that contains interpart expressions linked to a source part that is not loaded, the behavior of Siemens NX is to display a message indicating that the interpart expressions cannot be evaluated. This occurs because interpart expressions depend on data from the referenced part to function correctly. Without access to the source part, the software cannot retrieve the necessary values or parameters to compute these expressions, which leads to the system notifying the user of this limitation.

This response maintains the integrity of the workflow within Siemens NX, alerting the user to a significant issue that needs addressing before proceeding, ensuring that the design intent is not lost due to missing references. The use of interpart expressions relies heavily on the relationships between components, and being made aware of the absence of the source part is critical for both problem-solving and maintaining proper assembly constraints.