Individual rights currently being built up in respect of contracts offering the benefits mentioned in Article L. 143-1, but which have not been taken out as part of supplementary occupational retirement activities as defined in that same Article and in Article L. 382-1, may be transferred to another contract mentioned in Article L. 143-1, whether or not it has been taken out as part of the authorisation provided for in the same Articles, under the conditions and subject to the reservations set out in this section.