CITROEN DS4 Owner's Handbook Manual page 171

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.
Seat
Front passenger seat (c)
- fixed
- height adjustable
Outer rear seats (d)
Centre rear seat (d)
Weight of the child / indicative age
Less than 13 kg From 9 to 18 kg
(groups 0 (b) and 0+) (group 1)
Up to ≈ 1 year From 1 to ≈ 3 years
U(R1)
U(R2)
U
X
From 15 to 25 kg
(group 2)
From 3 to ≈ 6 years
U(R1) U(R1)
U(R2) U(R2)
U U
X X
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Child safety
From 22 to 36 kg
(group 3)
From 6 to ≈ 10 years
U(R1)
U(R2)
U
X