A major breakthrough in Civil 3D 2024 is the ability to directly link to .PKT files like an Xref. Previously, users had to manually re-import files every time a small change was made, which was a "clunky workaround" that often broke existing corridors.
If you are using , the management of these files has changed for the better.
: Autodesk provides free sample PKT files designed for learning and modification. These are excellent templates for understanding how to build input/output parameters. Download official sample PKT files .