Yeah, XHTML Strict Mode doesn't accept target="_blank".
If you don't want to keep using window.open everywhere, you can use rel="external" and some extra Javascript like the following, using JQuery:
$(document).ready(function() {
$("a[rel='external']").attr("target","_blank");
});
EDIT: To set all generated links:
$("a[rel='external']").ready(function() {
$("a[rel='external']").attr("target","_blank");
});
Or, without jQuery, you can use the script, found here:
function externalLinks() {
if (!document.getElementsByTagName) return;
var anchors = document.getElementsByTagName("a");
for (var i=0; i<anchors.length; i++) {
var anchor = anchors[i];
if (anchor.getAttribute("href") &&
anchor.getAttribute("rel") == "external")
anchor.target = "_blank";
}
}
window.onload = externalLinks;