17 I turn then to the question raised as to the competence of the appeal. The offence of importation of narcotics of which the respondent was convicted was an offence against the Customs Act 1901 (Cth), s 233B(1). Having regard to the fact that a commercial quantity of cocaine was involved, the offence was punishable under s 235(2)(c) of the Customs Act by "a fine not exceeding $750,000 or imprisonment for life, or both, or for such period as the court thinks appropriate". Therefore the sentence of life imprisonment is not a mandatory sentence but, under s 19AB(1)(b) and (d), and s 16(1), it was a federal life sentence in respect of which the court was obliged, if it did not make a recognisance release order, subject to s 19AB(3), to "fix a single non-parole period". By s 19AB(3) the court may decline to fix a non-parole period or make a recognisance release order if, "having regard to the nature and circumstances of the offence or offences concerned and to the antecedents of the person, the court is satisfied that neither is appropriate." In other words, the Court is to have regard to the very matters relevant to sentence generally in making this decision. Where, as in this case, a non-parole period is fixed, it is as defined in s 16(1) as: