Which type of reference plane is not created by the user in synchronous mode?

In synchronous mode, the base reference plane is an inherent part of the Solid Edge environment that is established automatically and is not user-generated. This reference plane serves as the foundational element upon which designs are built, allowing for stable and consistent geometry creation and manipulation throughout the design process.

The significance of the base reference plane lies in its role as the primary reference for the model, providing a stable platform for placing and orienting other features. Users can create their own custom reference planes and additional types such as survey planes or fixed reference planes as needed for specific modeling tasks. However, the base reference plane is a default element that exists independently of user input, which is why it distinguishes itself from the other reference plane options available in the software.