Treatment of prior period errors: retrospective restatement is required unless impracticable, with interim materiality assessed per period. Prior period errors are omissions or misstatements from failure to use reliable information available at approval. Immaterial prior-period or current-period errors are corrected in the current period. Material prior-period errors are corrected retrospectively by restating comparative amounts and adjusting opening balances of assets, liabilities and equity for each affected period; if the error predates the earliest presented period, restate that opening balance. If retrospective restatement is impracticable, apply corrections to the extent possible or prospectively. Interim reporting requires assessing materiality relative to the interim period.