The best way to mitigate the risk associated with unintentional modifications of complex calculations in end-user computing (EUC) is to execute copies of EUC programs out of a secure library. This will ensure that the original EUC programs are protected from unauthorized changes and that thecopies are run in a controlled environment. A secure library is a repository of EUC programs that have been tested, validated, and approved by the appropriate authority. Executing copies of EUC programs out of a secure library can also help with version control, backup, and recovery of EUC programs. Having an independent party review the source calculations, implementing complex password controls, and verifying EUC results through manual calculations are not as effective as executing copies of EUC programs out of a secure library, as they do not prevent or detect unintentional modifications of complex calculations in EUC. References: End-User Computing (EUC) Risks: A Comprehensive Guide, End User Computing (EUC) Risk Management