How is a 'fixed' relationship defined in a sketch?

A 'fixed' relationship in a sketch is defined as one that locks a sketch entity in place, preventing it from moving or changing shape during the design process. This is crucial for ensuring that specific geometric entities remain stationary relative to the rest of the sketch when modifications are made. By applying a fixed constraint, designers create a reference point or anchor for other entities, which can help in maintaining the intended design structure and relationships among the components.

The ability to lock entities in place is essential for managing the overall geometry of a design and ensuring that changes do not inadvertently alter important features. This is particularly important in complex sketches where many Entities are interdependent.

A fixed constraint makes it clear which part of the sketch is the foundation upon which other relationships or dimensions are built, thus enabling a more organized and predictable modeling environment.