Autodesk Subassembly Composer (SAC) is a standalone application that allows you to create complex, parametric subassemblies for AutoCAD Civil 3D without needing advanced programming skills

Properties: Used to adjust specific parameters (e.g., coordinates, link codes) for any selected object in the flowchart.

Flowchart: The logical "map" where you drag and drop tools to define the subassembly's structure.

Step 4: Add Conditional Logic for the Check Dam

Now we use the Flowchart tab.