ModifyField

  [DataEventHandler(tableStr(PurchAgreementHeader), DataEventType::ModifiedField)]
    public static void PurchAgreementHeader_onModifiedField(Common sender, DataEventArgs e)
    {
        ModifyFieldEventArgs    event = e as DataEventArgs;
        PurchAgreementHeader    purchAgreementHeader = sender as PurchAgreementHeader;
        FieldId                 fieldId = event.parmFieldId();
        date                    emptyDate;
        switch(fieldId)
        {
            case fieldNum(PurchAgreementHeader, BankGuarantee):
                if(purchAgreementHeader.BankGuarantee == NoYes::No)
                {
                    purchAgreementHeader.BankGuaranteeExpirationDate = emptyDate ;
                    purchAgreementHeader.BankGuaranteeNumber         = "";
                    purchAgreementHeader.Bank                        = "";
                }
                break;

        }
    }