PEUGEOT 508 Handbook page 156

Child safety
a: universal child seat, child seat that can be installed in all vehicles using a seat belt.
b: group 0, from birth to 10 kg. Shells seats and baby carriers cannot be installed in the front passenger seat.
c: consult the legislation in force in your country before installing your child on this seat.
U: seat suitable for the installation of a child seat secured using a seat belt and universally approved, "rearwards-facing" and/or "forwards-facing".
U (R): idem U, with the vehicle's seat adjusted to the highest position and as far back as possible.
X: seat position not suitable for installation of a child seat for the weight class indicated.
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