What is the effect of deleting a 'used' expression in NX Design?

When a 'used' expression is deleted in NX Design, it has a significant impact on the model. Specifically, the model will generate an error because the expression being deleted is referenced elsewhere in the design. Expressions in NX are often interconnected, meaning that if one expression is used as a parameter in another feature or calculation, its removal disrupts those dependencies. The model essentially relies on that expression for its integrity and calculations, leading to a model error to indicate that there is an unresolved reference. This ensures that designers are aware of the ramifications of deleting elements that are actively being utilized in their models, prompting them to address potential issues before proceeding.