NCV
From Memory Alpha, the free Star Trek reference
NCV is a prefix for Federation timeship registry numbers in the 29th century, similar to the NCC prefix commonly found in Starfleet in previous centuries.
One starship known to carry the NCV prefix is the Wells-class USS Relativity (NCV-474439-G). (VOY: "Relativity")
Since the USS Relativity appears to have at least seven previous vessels bearing its name, it is highly possible that those ships also have a NCV prefix for their registry numbers. Other Wells-class timeships most likely have NCV prefixes as well, though this is strictly speculation.
It is possible that the NCV prefix also applies to standard (non-time travel) starship registry numbers in the future Federation.
