Period of release to be reckoned as imprisonment for computing period of sentence served

The period during which a person is absent from prison under the provisions of this Act on a licence which is in force shall be reckoned as a part of the period of imprisonment to which he was sentenced, for the purpose of computing the period of his sentence and for the purpose of computing the amount of remission of his sentence which might be awarded to him under any rules in force relating to such remission.