Infinity and nested categories

Hi again everybody, well, I've asked it before, but I couldn't work on this at all. As some knows I have a system witch has a category system. The generic part of the site is handled by a generic module called contents... generic like products, services, company, etc. Where the content layout and structure is quite the same. Well suppose that I have this: http://www.the_company.com/site/products/product_one/requirements/requirements.html Where: site/ <---- the controller products/ <----- alias module for content module product_one/ <----- top category

requirements/    <----- nested category
            <---------- as many nested categories as needed
requirements.html <----- article is called searching using it without the .html, witch is used to know that it is an article and not a category. ('WHERE article_path='requirements' AND category_id='022')

My problem is that how can I handle those categories!!!!!!!!!!!!! and build a three of it. I am using PHP5 and MySQL 4.1 Regards, Bruno B B Magalhaes