問題：如何讓SF版驗證碼變成純數字？

解決方法：修改/Controls/ValidateCodeImage.aspx文件，找到以下代碼：

<div>
            <pe:ValidateCodeImage ID="ValidateCodeImage1" runat="server"
                ValidateCodeFontSize="10" ValidateCodeMaxLength="6" ValidateCodeMinLength="4"
                ValidateCodeLengthMode="static" />
        </div>

替換為

        <div>
            <pe:ValidateCodeImage ID="ValidateCodeImage1" ValidateCodeBoundString="0|1|2|3|4|5|6|7|8|9" runat="server" ValidateCodeSessionName="ValidateCodeSession"
                ValidateCodeFontSize="10" ValidateCodeMaxLength="6" ValidateCodeMinLength="4"
                ValidateCodeLengthMode="static" />
        </div>