Standard Interfaces
Standard interfaces are identified in Cubase VST by the names provided by their respective drivers.
Multi-port Interfaces
If you have a multi-port interface, each of its MIDI Out connectors appears as a MIDI Output in the Output list. Setting a Track to a certain Output routes all the MIDI Data on that Track to that specific MIDI Out connector on the interface.
Direct ConnectionsSome MIDI equipment provide “direct connections” to the computer, using serial or USB cables instead of actual MIDI cables. From Cubase VST’s point of view, these behave exactly like regular MIDI interfaces, i.e. each “Direct Output” appears in the Output list, named according to the respective driver.
For details, see the documentation of the MIDI equipment in question.