Descriptive is (in 95% of cases) the only sensible way.
Port traffic will vary as geopolitical, technological, population, and diplomatic changes happen and as demand varies. That means that some ports can lose traffic, some ports can gain traffic, and overall trade across all ports can either increase or decrease (usually increase in peaceful times, can decrease fast in war or disaster times). As trade varies due to various factors, traffic may switch from one main to a less used path, temporarily overloading the facilities on the less used path.
What particular loading/unloading/ship building/ship repairing/ship upgrading you can do at a given port is very demand/need driven (though policies of the Imperium and member planets as well as one supposes large corporations may drive some other capability changes to create a need or to meet a strategic concern).
And one thing to ponder:
"Have refined fuel available" - How much available? How long to get more? (the equivalent for yards is 'How many berths?', 'What TL gear can they easily get?', 'How big are the berths?', 'What's the existing backlog?').
There could reasonably be very feature-rich ports with low volume (a low pop garden world that the rich, the important, and the noble from all of the sector have staked out estates on). You could also have huge ports with more basic facilities - high pop worlds that are not super wealthy but need imports desperately. There could be shipyards with an attached port with them being the only population on a low grav planet or in an orbital facility - port does not need to be high volume as all it does is supply out-system parts and some stuff to support the workers. The yards themselves could be a fair size.
You want your method of describing ports to be one that:
- Allows the wide variations in ports
- Can grow and change as situations related to trade change without necessarily needing more than a revisit by an auditor/reviewer
- Supports cases like: The TL of your yard or part may have a lot to do with nearby planets of high tech manufacturing (or the lack thereof) - it's quite possible to see a port on a TL-11 world that can supply a lot of TL-13 goods from the high pop, TL D planet 1 jump away.
- Allows corporate/navy/etc ports to be documented but operate on different rules than the trading ports/ports of entry
As to the UPP:
Earth Circa 'the Covid era': <code for small experimental spaceport>-868975-8
Now, does that even come vaguely near describing the planet?
Over 140 countries
Law levels *all over the map* from none to 10+ (5 is my attempt to encompass 0 to 10+ law...)
Balkanized with many, many government types
It's not entirely useless, but when you go beyond the 3 physicals, it's really not worth a lot in any balkanized world or even a non-balkanized world that does not have global extensiveness of law or tech levels. And TL may be different in different regions of the planet and from aspect to aspect of technology.
So, yes, the UPP can give you a quick, very slightly useful, very possibly very, very broken view that may be of no value beyond the physical 3 stats.
I'd say the only utility of UPP is to give us physicals, gas giants, etc. and larger political boundaries on a map. Beyond that, it is a poor tool.
If you plan to have your players experience a world or understand the system and the worlds in it, you need a much better picture.
It's the difference between having a country described by a table with 'name, current population as of last census and maybe leaving out people we don't like' and CIA factbook entry or Encyclopedia entries.
If you want to do fun stuff on a planet, you would benefit from the sorts of write ups you got in Tarsus, the GT world booklets, etc. vs. the UPP. If you want to blow through, treat the place like a truckstop on I-90 (US interstate highway) and just roll on, the UPP may be sufficient.
That said, taking the UPP and moving to more codes (expanded codes) is itself problematic. What you really need is enough of a 'Fodor's Travel Guide To Regina' vs. a bunch of codes that might not crystalize into an understanding in the GM's head. You need some terse, but well crafted text to outline the important things for visitors.
TomB