How to generate a .DOC file in PHP with a Watermark

Is this even possible? I know it's possible to generate watermarks in PHP. Also, is there a site with a list of HTML tags that can be used in a doc file? I'm basically wondering how far you can go in a DOC file with html b开发者_C百科efore it breaks.

Have a look at http://phpword.codeplex.com/ It seems to have watermarks. I have't tried this one personally, but PhpExcel works great for me.