Here are some useful SWF File Format implementation websites. If you are looking at generating, writing and developing SWF thru the macromedia Flash 5 SDK, these websites are for you. I found these links while reading Colin Moock’s ‘ActionScript the Definitive Guide‘.
1. Macromedia Flash Player File Format (SWF) :: www.macromedia.com/software/flash/open/licensing/fileformat,
2. Open SWF :: www.openswf.org,
3. Ming :: www.opaque.net/ming,
4. Perl Flash :: www.2shortplanks.com/flash.