What type of Reference CSYS must be used to create an Offset - Datum CSYS for associativity?

To create an Offset - Datum Coordinate System (CSYS) for associativity in Siemens NX, the method typically involves using a Selected CSYS. This approach allows users to define a CSYS based on existing geometry or specific user-defined references in the design environment. By selecting a CSYS that is already established, one can ensure that the new Offset - Datum CSYS maintains a relationship with the original geometry, enabling any updates or modifications made to the original CSYS to be reflected in the new datum.

This choice is fundamental for maintaining design intent, as associativity is key to ensuring that changes dynamically propagate through the model. A Selected CSYS allows for flexible positioning and creates a dependable reference for subsequent features and assemblies, adhering to best practices in parametric modeling. In contrast, other types of CSYS, such as System, WCS, or Dynamic CSYS, do not facilitate the same level of associativity as they serve different purposes in the modeling environment. For example, the System CSYS is often fixed and based on the global coordinate system of the model, while a WCS is related to the user’s working coordinate system, and a Dynamic CSYS is more transient and based on user interactions without the same reliability for ongoing reference.