3.—(1) In calculating for the purpose of Part I of the 1993 Act the total period of time that must be served in custody under the substitute sentence, there shall be deducted from that period any period of time served in custody under the original sentence.
(2) In calculating for the purpose of Part I of the 1993 Act the total period of time during which a person is, or is to be, released on licence in respect of the substitute sentence, there shall be deducted from that period any period of time–
(a)served in custody under the original sentence which is surplus to that which the person requires to serve in custody under the substitute sentence taking account of paragraph (1) of this article;
(b)during which the person was released on licence under that Part of that Act in respect of the original sentence before the date on which (but for that release) that sentence would have been served in full; and
(c)during which the person was released unconditionally under that Part of that Act in respect of the original sentence before the date on which (but for that release) that sentence would have been served in full.
(3) In calculating for the purpose of Part I of the 1993 Act the total period of time during which a person is, or is to be, released unconditionally in respect of the substitute sentence, there shall be deducted from that period any period of time–
(a)served in custody under the original sentence which is surplus to that which the person requires to serve in custody under the substitute sentence taking account of paragraph (1) of this article;
(b)during which the person was released on licence under that Part of that Act in respect of the original sentence before the date on which (but for that release) that sentence would have been served in full; and
(c)during which the person was released unconditionally under that Part of that Act in respect of the original sentence, before the date on which (but for that release) that sentence would have been served in full.