source.php question

I was on php.net and i was looking at the source of some of pages with the source.php link at the bottom of each page, but when i went to the www.php.net/manual/en/ pages, the source would not show, the pages in www.php.net/manual/ would although! I was specifally looking at the comments system you have on each manual page, and i wanted to implement a similar system to my website. Is there a way i can look at how you have done this? Can you help or change this?? Thanks in advance Rory Lawson