na_0020: Number of inputs to variant subsystems
Simulink® requires variant subsystems to have the same number of inputs. However, the variant subsystem might not use all of the inputs. In these instances, terminate the unused inputs with the Terminator block.
By Task > Modeling Standards for MAAB > Model Architecture > Check unused ports in Variant Subsystems
For check details, see Check unused ports in Variant Subsystems (Simulink Check).