The exact provisions of the relevant Interpretation Act indicate when and how extrinsic materials may be used.

For example, the Interpretation of Legislation Act 1984 (Vic) provides (in s 35) that consideration may be given to any matter or document that is relevant including:

• reports of proceedings in any House of Parliament;
• explanatory memoranda or other documents laid before or otherwise presented to any House of the Parliament;
• reports of Royal Commissions, Parliamentary Committees, Law Reform Commissioners and Commissions, Boards of Inquiry or other similar bodies.