Hey,
for MSFS there are 3 major AI addons avialble (AIG, FSLTL, FSTraffic) all of those support the use of the atc_parking_codes
varible that is part of the fltsim-section inside the aircraft.cfg files.
Adding the option to the SDK to add those Codes to the parkings as well (The BGL files and the compiler support it already) will boost the immersion at the airports.