What DLP does
Microsoft Purview DLP scans content for sensitive information types (TFNs, Medicare numbers, credit cards, BSB / account numbers, passport numbers, etc.) and applies policies — block, warn, log, override-with-justification — when matches occur. Policies can target specific scopes (sites, groups, distribution lists) and conditions (external recipient, anonymous link, sensitivity label).
Australian sensitive information types
Microsoft ships AU-specific sensitive info types: Australian Tax File Number, Australian Medical Account Number, Australian Bank Account Number, Australian Driver's Licence Number, Australian Passport Number, Australian Company Number, ABN. These detect with high precision when used inside DLP policies. For Privacy Act reasonable-steps, having DLP policies for these AU types is now baseline.