Auditing concept pertaining to the assessment of control risk, control testing and substantive testing related to the collection of evidence. Used of Electronic Data Processing (EDP) into processing of accounting data has effects on controls and the audit trail. The independent auditor must evaluate these effects on the element of the control structure and must be aware of how EDP may change the audit trail. Additional controls that have been specified in response to the effects of EDP on the processing of accounting data include general and application control. Computer auditor, the computer and computer testing can play major roles in controls and substantive testing.