(1) This section
applies if a sentence of detention imposed on a person (the second sentence )
is to be served cumulatively upon another sentence of detention (the first
sentence ) and section 122 does not provide for one earliest release day for
both sentences.
(2) In determining
whether a person has been in custody under a sentence for the minimum period
required before the offender can be released, time served in custody after the
second sentence is imposed counts —
(a) if
the earliest release day for the first sentence has not been reached, as
service under that sentence until the earliest release day for that sentence
is reached;
(b)
after the earliest release day for the first sentence has been or is reached,
as service under the second sentence until the earliest release day for the
second sentence is reached.
(3) Once the earliest
release day has been reached for each sentence for which there is an earliest
release day, time served in custody counts as service under the first sentence
until that sentence has been served, so far as it is required to be, and after
that, as service under the second sentence until that sentence has been
served, so far as it is required to be.