5.56mm 'Limit, Low Energy'

Can anybody supply any information about this Sellier & Bellot 5.56mm round? If its not clear in the photograph it has a white painted tip. The bullet is non-magnetic CN. Hand written on the side of the case were the words ‘Limit, Low Energy’

I will postulate that it refers to minimum pressure for reliable gun functioning in a certain weapon.

Is the jacket material unusual for this manufacturer?