Always Valid Lightbox is a Lightbox plugin whose markup adapts to the WP site's Doctype, in order to always provide valid HTML markup.
Always Valid Lightbox is a Lightbox plugin which can automatically add the HTML attributes needed to trigger the effect on content image links, so that the user never has to add a class or an attribute to his content images in order to make the lightbox work.
Also, AVL allows the user to chose the attributes he wants inserted on his image links, depending on the Doctype declaration used in the website header.php template. This way, the lightbox never generates markup validation errors at the W3C Validator test.
The jQuery lightbox effect is an adaptation based on David Ryan's jQuery lightbox tutorial : http://dryan.com/articles/jquery-lightbox-tutorial/