There's a bit of information on undocumented features onblitzcoder
http://www.blitzcoder.com/cgi-bin/code/code_listentries.pl?id=UD
I wouldn't say it's complete, but ta least it does exist.
Then for more information on specific features, google is your friend. By example you can find quite a lot of thread about handle/object:
http://www.google.com/search?hl=fr&q=site%3Ablitzbasic.com+handle+object&btnG=Recherche+Google&meta=
http://www.blitzcoder.com/cgi-bin/code/code_listentries.pl?id=UD
I wouldn't say it's complete, but ta least it does exist.
Then for more information on specific features, google is your friend. By example you can find quite a lot of thread about handle/object:
http://www.google.com/search?hl=fr&q=site%3Ablitzbasic.com+handle+object&btnG=Recherche+Google&meta=