The Revit API platform can be leveraged by customers and third-party developers to create their own connections and integrate them into Revit.
Revit supports add-ins for user designed parametric structural connections. Structural connection add-ins are API driven user interfaces to view detailed structural connection geometry and to modify additional parameters in the Revit modeling environment.
Unless structural connection add-ins are installed, only the symbolic generic connection is available. Some add-ins may require a subscription.
Appropriate Revit add-ins must be installed to open models with add-in structural connections. Otherwise, the connection will display but cannot be edited. If you unload an add-in structural connection from the Structural Connection Settings dialog, any instance of that connection will be deleted from the model.