FDA 21 CFR Part 11 Part11.AuditTrail: Audit trail requirements - secure computer-generated time-stamped (21 CFR §11.10(e))

Section 11.10(e) audit trail requirement: USE OF SECURE + COMPUTER-GENERATED + TIME-STAMPED AUDIT TRAILS to independently record the date and time of operator entries and actions that create + modify + or delete electronic records. Record changes must not obscure previously recorded information. Audit trails must be maintained for as long as required for the subject records (typically following the underlying record-retention requirement which can be 2 years (clinical) + 5 years (medical device) + or longer depending on the regulated activity) + must be AVAILABLE FOR AGENCY REVIEW AND COPYING. Audit trails must include: WHO (user identity); WHAT (action - create + modify + delete + view as appropriate); WHEN (computer-generated time stamp - server-side clock + synchronized to authoritative time source NTP); WHERE (system + module + record); BEFORE / AFTER VALUES (for modification audit); WHY (reason for change where applicable + commonly required by company SOP). The 'WHO + WHAT + WHEN + WHERE + WHY' acronym (5W) is industry-standard for Part 11 audit trail design. FDA inspectors routinely review audit trails for QC + clinical + manufacturing systems + focus on operator-action coverage + tamper-evidence + time-source integrity.