Auditor's allocate the preliminary judgment about materiality to financial statement segments rather than by financial statements as a whole

What is the term for the auditor's allocation of preliminary misstatement to account balances? What are three difficulties auditors face when allocating materiality to balance sheet accounts?
What will be an ideal response?

Performance materiality is the term for the auditor's allocation of the preliminary judgment of materiality to any given account balance. The three difficulties auditors face when allocating the preliminary materiality to account balances are:
1. Auditors expect certain accounts to have more misstatement than others.
2. Both overstatements and understatements must be considered.
3. Audit costs can affect the allocation.