问题：如何让SF版验证码变成纯数字？

解决方法：修改\Controls\ValidateCodeImage.aspx文件，找到以下代码：

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

替换为

        <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>