How to validate ImageButton through W3C ?

This is a problem caused by W3C running validation whilst reading the HTML rendered for a simple broswer like netscape, Image button's source code render like this
<asp:ImageButton ID="IbSubmit" CssClass="class" BorderWidth="0px" runat="server" ImageUrl="~/images/img1.jpg" />
The "BorderWidth="0px" " is aproblem it wont validate through W3C .
Try the following
Right click on the project folder and Add App_Browsers folder (select it from Add Asp.NET Folder)
Right click on the App_Browsers folder and choose Add New Item and add Browser File
Its content like this

<browsers>

<browser id="NewBrowser" parentID="Mozilla">

<identification>

<userAgent match="Unique User Agent Regular Expression" />

identification>

<capture>

<userAgent match="NewBrowser (?'version'\d+\.\d+)" />

capture>

<capabilities>

<capability name="browser" value="My New Browser" />

<capability name="version" value="${version}" />

capabilities>

browser>

<browser refID="Mozilla">

<capabilities>

<capability name="xml" value="true" />

capabilities>

browser>

<browser id="w3cValidator" parentID="default">

<identification>

<userAgent match="^W3C_Validator" />

identification>

<capture>

<userAgent match="^W3C_Validator/(?'version'(?'major'\d+)(?'minor'\.\d+)\w*).*" />

capture>

<capabilities>

<capability name="browser" value="w3cValidator" />

<capability name="majorversion" value="${major}" />

<capability name="minorversion" value="${minor}" />

<capability name="version" value="${version}" />

<capability name="w3cdomversion" value="1.0" />

<capability name="xml" value="true" />

<capability name="tagWriter" value="System.Web.UI.HtmlTextWriter" />

capabilities>

browser>

browsers>