Which term describes constant, non-numerical relationships between parts of a geometric figure?

The term that describes constant, non-numerical relationships between parts of a geometric figure is geometric constraints. These constraints define how elements of the design relate to each other in a way that preserves their geometric relationships, regardless of their size or scale. For instance, they can dictate that two lines are parallel or that points are collinear, ensuring that those relationships remain intact as the design evolves.

Geometric constraints allow designers to maintain the integrity of the design by establishing fixed relationships, which can be particularly useful in parametric modeling where the dimensions may change but the relationships do not. This is crucial in engineering design, as it aids in automatically updating a design when certain parameters are altered, ensuring coherence in the overall structure.

Other options describe different aspects of design constraints. Numeric constraints are specifically about the measurements assigned to parts of the geometry, while dimensional constraints focus on the specific length or size measurements assigned to the elements. Structural constraints deal with the physical limitations imposed by materials and design intents but do not address the geometric relationships directly.