What type of reference plane is NOT created by the user?

A base reference plane is a type of reference plane that is automatically created by the software when a part or assembly is initiated. It typically serves as a foundational element for modeling and is aligned with predefined coordinate system axes. The fundamental purpose of the base reference plane is to provide an origin from which other geometry can be referenced, ensuring proper alignment and positioning within the 3D environment.

In contrast, the other reference planes, such as work reference planes, construction reference planes, and custom reference planes, are user-defined and created based on specific modeling needs. Users create these planes to help facilitate complex designs and achieve precise geometry modeling, allowing for greater flexibility in the designing process. Hence, the unique characteristic of the base reference plane is that it is inherently generated by the system, making it distinct from other reference planes that rely on user input.