In reply to acpatel5:
I’m not sure what you mean by “part of the interface itself”. All signals inside an interface are part of the interface.
Do you mean signals specified as inputs/outputs as part of a port list, similar to modules? In this case, you would specify the direction just like you would a module.
In order to use a modport, you need to create an instance of the interface, and you would connect the ports as required.