Which default Reference Set is available if no additional reference sets have been defined?

The default Reference Set labeled "Entire Part" is the primary set that includes all the components and features of a model in Siemens NX. When no additional reference sets have been defined, this reference set is the one that is used by default for viewing and working with the part.

The "Entire Part" reference set ensures that users can access all available geometry and attributes of the model without any constraints. This is crucial for tasks like creating assemblies, modifying designs, and analyzing complete models without needing to switch between different reference sets.

In contrast, the "Lightweight" and "Partial" reference sets focus on specific portions of a model or enable a more efficient way of handling larger datasets by loading only essential information. While "All" may seem comprehensive, it does not represent a specific reference set within the context of default settings. Therefore, "Entire Part" stands out as the encompassing selection that serves as the foundation for ensuring that accessibility to the complete model is maintained for various tasks.