RewriteRule ^forum/([-_!~*'()$a-zA-Z0-9]+)/?$ ./index.php?pretty;board=$1.0 [L,QSA]
RewriteRule ^forum/([-_!~*'()$a-zA-Z0-9]+)/([0-9]*)/?$ ./index.php?pretty;board=$1.$2 [L,QSA]

# Rules for: topics
RewriteRule ^forum/([-_!~*'()$a-zA-Z0-9]+)/([-_!~*'()$a-zA-Z0-9]+)/?$ ./index.php?pretty;board=$1;topic=$2.0 [L,QSA]
RewriteRule ^forum/([-_!~*'()$a-zA-Z0-9]+)/([-_!~*'()$a-zA-Z0-9]+)/([0-9]*|msg[0-9]*|new)/?$ ./index.php?pretty;board=$1;topic=$2.$3 [L,QSA]