Thanks!
Ran across some scanned notes from 1987 where I labeled a station 'Illishneer Highport', but hadn't, at the time, encountered any other Traveller material than a few LBBs and seen a few modules. Probably picked it up from a novel (or Star Frontiers?).
Don't have the TTA - curious if anyone could confirm whether it's downport refers to the starport as 'Downport' by name or as a downport, or does it refer to a city/starport combination (ala Downbelow Station from C. J. Cherryh - which, IIRC, would have been early 80's - maybe that is my original source)?
So basically no mention of Highport is recollected... starports could be either, with no rules to support determination (corrosive atmo worlds seem a likely candidate for defacto highports and shuttles to surface).
Regards the implication that A/B/C starports have shuttles, that seems reasonable for many stations, but unusual, for reason of a highport, for atmo 0 worlds (though they could also be for space stations, habitats, factories, etc. for any atmo).
Also, starports have no minimum dton capabilities listed anywhere, aside from implication by design rules that type A's must support over 100 dtons for jump capable ships?