While trying to solve a validation issue in one of my web sites I came across the following forum posting. It was stated so well that I decided to re-post it here. I want to encourage my readers to understand that when a page doesn’t pass validation, it doesn’t mean that the page is “broken”. Please read on…
Validation is a tool. It is not a goal. It is for catching syntax errors. It is for you to determine whether to worry about the error or not.
The animations module is in working draft status.
Status of this document
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
Emphasis added.
It would be foolish for vendors to implement a module that is likely incomplete and certain to be modified in ways that would affect that implementation. That is why we have the -[vendor]- prefix. It’s a temporary implementation until the dust settles.
If your client is insisting on a validation button, you’ll have to explain why that’s not possible. Using css3 is a progressive enhancement; in this case from both sides. Older browsers won’t support css3 animations, and css3 won’t validate the proprietary prefix that allows for working draft properties that are not a part of the specification yet.
Gary Tuner, (Moderator on http://csscreator.com)
Source: http://csscreator.com/topic/w3c-validator-and-css3