The exceptional reduction in sentence provided for by article 721-3 as well as that provided for by article 721-4 may be granted in one or more instalments without exceeding one third of the sentence handed down. To determine the maximum quantum, account is taken of all sentences to be served or in prison on the date of the request. In all cases, the sentence enforcement judge or court shall specify in its decision the sentence or sentences taken into account to calculate the maximum quantum of the exceptional sentence reduction.
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