Using FRFOS on your shipping documents
FRFOS is the code you will normally see for Fos-sur-Mer on carrier paperwork. Bookings and bills of lading print the port of loading and port of discharge as UN/LOCODEs, and carrier schedule and tracking feeds use them too. The first two letters, FR, are the ISO 3166-1 country code for France; the last three identify the place.
A UN/LOCODE names a place, not a berth. Where a port city has several container terminals, UNECE often gives the terminals their own codes alongside the city code, so a booking can legitimately show a code you didn’t expect. Take the code from the carrier booking, not the one that looks most like the port name.
Schedule D codes exist only for US ports, so Fos-sur-Mer doesn’t have one. If Fos-sur-Mer is your origin, the Schedule D code that matters is your US port of entry’s: every US port page in this tool shows it where CBP publishes one.