入力規則
Validation^ xlValidation; xlRangeC = (Range^)ws->Range["A1","A1"];
xlValidation = xlRangeC->Validation;

xlValidation->Delete(); // 必ず先にクリアする
xlValidation->Add(
XlDVType::xlValidateList,
XlDVAlertStyle::xlValidAlertStop,
XlFormatConditionOperator::xlEqual,
"選択肢,選択肢",
""
);

xlValidation->ShowError=bool // true:無効データの警告あり false:なし