Star ports are classed from A to E, with A being the highest quality. A world without a star port is designated as X.
Star ports with an 'o' suffix are orbital only, with no planetary base. This allows easier docking, but may mean harder access to the planet's surface. Eo and Do ports are generally only found in asteroid belts, or built into larger asteroids.
Star ports with a 'g' suffix are ground only. This only applies to A, B and C ports, since D and E are usually ground only.
Class A starports are the largest and most complete class of star port. They generally require a supporting population of millions.
They have a full set of dockyards for the construction and repair of starships, as well as leisure, trade and security facilities.
A class A starport is often a station kilometres in size, in orbit around a planet or part of an asteroid.
Class AA (“double-A”) and AAA (“triple-A”) ports have the same capabilities, but are larger and have more of them.
Class B starports are large, with a considerable amount of through traffic and trade. Like A-class ports, they generally require a supporting population of millions.
The main difference between B and A ports is that B ports lack the construction dockyards of A ports. B's will generally provide some facilities for repair, but not full ship construction.
Class BB (“double-B”) ports exist, and denote a much larger capacity than standard B ports, but without any extra types of facilities (simply more of what is usually there).
Class C starports are the lowest class of 'proper' starport, generally consisting of both orbital and planet-side facilities. Though they lack facilities for ship building and repair, they tend to have everything else a traveller needs in terms of trade, information and recreation.
Class D starports are limited in scope, and are often ground side only (though Do ports exist, especially on asteroids or around uninhabitable worlds). They will have basic refuelling and warehousing facilities, with a few low quality hotels and basic entertainment.
They are not places where a long stop-over is desirable.
Class E starports are the most basic, consisting of basic re-fuelling and little else. They may even consist entirely of a cleared spot of land, with some free standing fuel tanks. The main differentiation between type E and D starports is that the former often won't have any permanently manned facilities, they tend to be a help your-self affair, with visitors expected to leave things in the same state that they left them.
Like all starports, they will have a radio beacon which will respond to pings, allowing them to be easily discovered by approaching craft. They can typically be detected from low orbit - often to 1,000 to 10,000 kilometres.