Q. The system uses a numerical addressing schema for pages. Why?
A. The numerical schema is where pages have addresses like www.domain.com/53. This contrasts with hand-built sites that often have addresses like www.domain.com/sales.htm.
There are several reasons for the numerical schema, all to do with the need for scalability and flexibility over the lifecycle of the site.
Firstly, by separating the name of the page from the address, it is easy to change the page name without breaking any links to the page - links that can be from other pages in the site, or from other sites.
Secondly, we don't need to worry about name collisions - where two pages need to be called the same thing, there's no risk of one page accidentally overwriting the other. Name collisions may seem unlikely, but as sites grow and different individuals are delegated responsibility for different sections, administrators may not even be aware of the existence of all the other pages.
Q. Surely visitors will be confused by the numbering?
A. Visitors should only be vaguely aware of the numbering. They will be browsing to the site, and following the textual and graphical links within the site, not concentrating on the page addresses themselves.
If you do need to direct visitors to a particular page, you have the option of giving them the numerical address, which is nice and short if they need to type in it, or using the DirectURL system which aliases textual names to the pages.
Q. What about search engines? - I've heard they care about the page name.
A. Yes, they care about the page name - the HTML Title tag that appears in the top of the window, and obviously they look at the page content and meta tags, but they are quite used to numerical addressing schemes, and don't particularly worry about the addresses themselves. The two aspects of the page address that search engines concentrate on are the domain name, and the depth of the address (how many / characters are in it). Clearly the numerical schema doesn't affect the domain name, and the schema keeps all pages at the highest level, which search engines prefer.
Q. So is this a unique feature of the system?
A. Not at all. In fact, most sites of any substance use numerical addressing of one sort or another, as they need to handle the scalability and resilience issues detailed here.