Final answer:
AU 319 requires auditors to know the internal controls of a company to evaluate control risk, detect weaknesses, and design audit procedures.
Step-by-step explanation:
AU 319 requires auditors to understand internal control to plan an audit effectively. Understanding internal controls is a pivotal part of an auditor's assessment of control risk, which involves evaluating the chances that errors or fraud may occur within a company's financial statements due to inadequate internal controls. An auditor must identify potential weaknesses in the control system and design specific audit procedures to address these weaknesses. The depth of understanding needed includes how controls are designed, whether they have been implemented, and how they manage financial reporting risks.