CITROËN C4 Handbook page 160

Safety
Locations for child seats secured using the seat belt
In accordance with European regulations, this table indicates the options for installing child seats secured using the seat belt and universally approved (a)
in relation to the weight of the child and the seat in the vehicle.
Front passenger seat (c)
- fixed
- height adjustable
Outer rear seats (d)
Centre rear seat (d)
158
Seat
(groups 0 (b) and 0+)
Weight of the child / indicative age
Less than 13 kg From 9 to 18 kg
(group 1)
Up to ≈ 1 year From 1 to ≈ 3 years
U(R1) U(R1)
U(R2) U(R2)
U U
X X
From 15 to 25 kg From 22 to 36 kg
(group 2) (group 3)
From 3 to ≈ 6 years From 6 to ≈ 10 years
U(R1) U(R1)
U(R2) U(R2)
U U
X X