VOY
Ocean freightVoyage number
The code a shipping line gives to one specific trip of a vessel.
In practice
Written with the vessel name, for example MV Example V.045E where E means eastbound. Needed on the B/L, permit, and tracking. A vessel keeps its name across voyages so the voyage number is what identifies the sailing.
Seen in the wild
Vessel/Voy: MAERSK TAURUS 245W.