(1) A person who, by reason of section 89, is subject to the requirements of this Part shall be so subject for the period referred to in subsection (3) or, in the case of a person referred to in subsection (2) or (3) of section 89, so much (if any) of that period as falls after the commencement of this Part.

(2) Subsection (1) is subject to section 93.

(3) The period mentioned in subsection (1) is the period, beginning with the relevant date, of -

(a) 12 years if the sentence imposed on the person in respect of the offence concerned is one of imprisonment for life,

(b) 7 years if the sentence imposed on the person in respect of the offence concerned is one of imprisonment for a term of more than 10 years but not one of imprisonment for life,

(c) 5 years if the sentence imposed on the person in respect of the offence concerned is one of imprisonment for a term of more than 5 years but not more than 10 years,