In Blender’s Freestyle, a line set filters which edges are drawn using criteria like visibility, face marks

https://wiki-cable.win/index.php/What_Contractors_Look_For_in_a_Reliable_HVAC_Line_Set

In Blender’s Freestyle, a line set filters which edges are drawn using criteria like visibility, face marks, and material boundaries, allowing separate stroke styles for silhouettes and creases.