Código:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="es">
<head>
<title>basura</title>
<link rel="stylesheet" href="a.css" type="text/css"/>
</head>
<body>
<div id="background">
<img src="principal.jpg" id="imgw" usemap="#map" title="Presiona ″entrar″ en la
imagen, para acceder al sitio" alt="" />
<map name="map">
<area shape="rect" coords="389.4,303.6,510.6,339.7" href="principal.html" alt="Click para
entrar" />
</map>
</div>
</body>
</html>
Result: Failed validation, 1 Error
File: upload://Form Submission
Encoding: utf-8
Doctype: XHTML 1.0 Strict
Root Element: html
Root Namespace:
http://www.w3.org/1999/xhtml
Line 21, Column 15: required attribute "id" not specified.<map name="map">
The attribute given above is required for an element that you've used, but you have omitted it. For instance, in most HTML and XHTML document types the "type" attribute is required on the "script" element and the "alt" attribute is required for the "img" element.
Typical values for type are type="text/css" for <style> and type="text/javascript" for <script>.
Entiendo que no le pongo ID, pero, porque lo necesita?, es decir, no le quiero dar un 'estilo' a un mapa de imagen, para que lo necesitaria?