OA. The initials of the auditor adjacent to the audit procedures in the audit program used to indicate who performed the procedures OB. The initials of the auditor on a written statement in the form of a memorandum wood to indicate who prepared the statement OC. Symbols used on an audit schedule that provide cross reference for purposes of organizing and filing OD. Symbols used on an audit schedule that provide additional information or details of audit procedures performed. An explanation of the tick mark must be included at the bottom of the audit schedule to indicate what was done and who did it