The most important thing for an IS auditor to review when evaluating the accuracy of a spreadsheet that contains several macros is the formulas within macros. Macros are sequences of commands or instructions that can automate tasks or calculations in a spreadsheet. Formulas are expressions that perform calculations on values or data in a spreadsheet. The accuracy of a spreadsheet depends largely on whether the formulas within macros are correct, consistent, and complete. The IS auditor should review the formulas within macros to verify that they produce the expected results and do not contain any errors or inconsistencies. The other options are not as important as formulas within macros, as they do not directly affect the accuracy of a spreadsheet. Encryption of the spreadsheet is a security control that can protect the confidentiality and integrity of the spreadsheet, but it does not ensure its accuracy. Version history is a document control feature that can track and manage changes to the spreadsheet, but it does not verify its accuracy. Reconciliation of key calculations is a validation technique that can compare and confirm the results of calculations with other sources, but it does not evaluate the accuracy of formulas within macros. References: CISA Review Manual (Digital Version), Chapter 3, Section 3.2

Section: Protection of Information Assets
Explanation:
A checksum calculated on an amount field and included in the EDI communication can be used to identify
unauthorized modifications. Authenticity and authorization cannot be established by a checksum alone and
need other controls. Nonrepudiation can be ensured by using digital signatures.

If proper identification and authentication are not performed during access control, no accountability can exist for any action performed.