VSOP (Very Superior Old Pale), also called Reserve
A V.S.O.P ( for Very Superior Old Pale ), also called Reserve, is a cognac which youngest eau-de-vie is between four and a half and six and a half years old.
A Cognac may be sold only when its youngest eau-de-vie reaches a minimum of two and a half years old, as of the first day of October following the harvest of the grapes.
Only the years of storage in oak barrels count to determine its age. Once transferred into glass, the Cognac stops maturing . It stands still.
Note that VSOP can be very good cognacs and some of them can be superior to many XOs. Some of the best value Cognacs are indeed VSOPs