It’s good practice to always make sure that each page on your site validates to its proper doctype. Recently I noticed that some pages on a site I did that use to validate no longer did. It was giving me an error saying that it didn’t know how to decode Content-Encoding ‘none’. This was saying that I wasn’t declaring the encoding at the top of my page. The thing is I was. Here is what the problem was. I am using php and have an external php page that contains functions on it that are used by the page and I was including that page at the top of the document. The problem with this was that it was above the doctype declaration. All I had to do was move it down one line and that fixed it. I’m not sure if something has changed with the validation because it use to validate, but if you run into this problem just move it down one line. Here is an example:
Before:
<?php include_once(“my-file.php”);?>
<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>
After:
<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>
<?php include_once(“my-file.php”);?>
PS
I use a cool plugin for Firefox called Web Developerthat has a built-in tool that will validate your page straight from the W3C Validator. If you are not currently using this I suggest checking it out!