Although it does at first seem correct to look at airports for the
present day starport, I think that it is run to does so, Ports are a
better move, Using British Examples, Portsmouth and Southhampton
would be Class A starports, Presence of Miltary Dockyards, Civil
Services Major ports. Dover I believe would be a Class B port, lack
of major Naval Forces. C and D ports are the small fishing towns
around the cost. E type ports are any Coastal town that Has a point
to launch a boat from but nothing else.
X class places are any location on the coast away from Life,
Dave