Ann: Trading Halt, page-68

Reasons for purging

Your orders will be purged from the market when:

• the order expires; (typically after nine weeks)
• the order has been entered as a day-only order;
• the order price is 60% away from the latest market price;
• the security has been suspended;
• the security had been delisted;
• the security has been reconstructed;
• the security has had a basis change of quotation (e.g. ex-dividend; ex-entitlement; ex capital return, etc.)

Source: https://www.stateone.com.au/faq.aspx