Adds an attribute to an XHTML element. The collection of element-specific attributes for the System.Web.UI.XhtmlTextWriter object is referenced by the XhtmlTextWriter.ElementSpecificAttributes property.
Use the XhtmlTextWriter.AddRecognizedAttribute(string, string) method to add an attribute to an XHTML element. The added attribute can then be recognized and rendered by the System.Web.UI.XhtmlTextWriter object. To prevent the writer from rendering a common attribute of an XHTML element, use the XhtmlTextWriter.RemoveRecognizedAttribute(string, string) method.