What it does
Currency Determination No. 4 of 1997 is a technical instrument made under subsection 13A(1) of the Currency Act 1965 (the Determination). The instrument, signed by the Assistant Treasurer on 28 July 1997, takes effect on 29 September 1997 (see the opening recital and clauses 1 and 2). Its operative effect is to set out detailed physical and design specifications for a set of Australian coins by reference to denomination, standard composition, standard weight and allowable variation, dimensions (diameter and thickness), shape, edge treatment, obverse and reverse designs (see clause 3 and the Schedule, Part 1).
Mechanically, the Determination does four things. First, it lists coin kinds in a schedule (Part 1) and for each kind prescribes the metal composition (for example "Copper, zinc, aluminium and tin", "99.9% silver", "99.99% gold"), a target standard weight with an allowable variation in grams, diameter in millimetres, thickness in millimetres, and coded design features (shape, edge, obverse and reverse) (clause 3 and Schedule, Part 1). Second, Part 2 of the Schedule explains the coded design features (for example S1 means circular; E1 means milled; E5 is a plain edge with a specified inscription; O3 and O4 describe particular obverse effigies and inscriptions; R44-R48 specify reverse images and inscriptions). Third, clause 4 states expressly that the Determination "does not affect any other determination of the specifications of a coin", so it operates alongside other Currency Determinations. Fourth, the instrument is confined to technical specification; it does not itself state legal tender status, price, sale arrangements or penalties in the text of the Determination.
Concretely, the Schedule lists multiple $5 coins with two different base-metal specifications and two silver $5 variants, plus a $100 gold coin. For example, a $5 coin in copper, zinc, aluminium and tin has a standard weight of 20.00 g ± 0.50 g, diameter 38.90 mm, thickness 2.65 mm, shape S1, edge E1, obverse O3 and reverse R44 or R45 depending on the row (see Schedule, Part 1). A 99.9% silver $5 has standard weight 31.635 g ± 0.50 g, diameter 40.60 mm, thickness 4.00 mm, shape S1, edge E5 (plain with inscription "GAMES OF THE XXVII OLYMPIAD" evenly spaced around the edge to read with the reverse facing up), obverse O4 and reverse R46 or R47. The $100 coin is 99.99% gold, weight 10.021 g ± 0.020 g, diameter 25.10 mm, thickness 2.40 mm, shape S1, edge E1, obverse O4 and reverse R48. The Part 2 explanations reproduce the exact text of inscriptions and design motifs for obverse and reverse codes (for example the obverse descriptions include the words "ELIZABETH II", "AUSTRALIA 2000", and in O4 an Arabic numeral denomination followed by the word "DOLLARS").