SYSML17 — SysML-1.6: Figure D.25 has the type Fuel for both an in Port and an out Port on FuelTankAssembly (and it is not ideal to have same name as the Classifier that flows)

Figure D.25 Detailed Internal Structure of Fuel Delivery Subsystem (Internal Block Diagram)

Has the type Fuel for both an in Port and an out Port on FuelTankAssembly

And it is not ideal to have same name Fuel as the Classifier Fuel that flows.

I happen to use the prefix convention F_ for Ports that have flows (only) of one Classifier, so in this case F_Fuel and ~F_Fuel