Opel Vivaro Manual page 49

U = Suitable for universal category restraint systems for use in this weight and age class, in conjunction with three-point
seat belt.
< = Seat with ISOFIX mounting available. When mounting an ISOFIX child restraint system, only systems that have been
approved for the vehicle may be used.
X = Seat position not suitable for children in this weight and age class.
Seats, restraints 49