SEO by the SEA - Google Patent on Web Spam, Doorway Pages, and Manipulative Articles

Detailed information from Bill Slawski on a newly approved Google patent. I found the information under the section Individual Document Signals / History of the document very interesting. This certainly points to the algorithm picking up changes an SEO might make to the text of a web page. The "history of the document" and "anchor text" sections were very interesting as to what level of change on the page might trigger a flag by the search engines.
SEO by the SEA - Google Patent on Web Spam, Doorway Pages, and Manipulative Articles