Hi rhumbaflappy,
I think, your post may need to be detailed (World is not not only “ICAO”) not to irritate your Repliers.
If you want to Request at Zendesk, then you may better only request to extend the Microsoft internal Airport Code format e.g. for additional usage of Psydo(!) ICAO codes, as e.g. used in France or Germany and other countries for very small Airfields. The standardized ICAO codes are (and will stay) limited to only 4 Characters.
See also:
But the World Airports are not only identified by 3-, 4- or 5-character limited ICAO or IATA Standards.
It will be necessary to cover all(!) of them by Microsoft specific internal Airport Code format.
Always Happy Landings,
Captain Warstein