Nils, it's been on their todo list for some time ... I think SQL 99 calls them recursive queries or something like that, I'll need to do some research.
Frank, you should just take the Oracle sortkey code for forums, look in forums/sql/oracle/forums-messages-create.sql and forums-tree-create.sql. Also acs-kernel/sql/oracle/tree-create.sql which creates the underlying package to manipulate keys.
RAW is a form of variable length byte storage that doesn't suffer from collation issues as does VARCHAR when you're using multibyte characters. They're used much like VARCHARs as you'll see when you inspect the code.
Still, it would be best to use native Oracle CONNECT BY queries I believe as we've done everywhere in the toolkit other than in forums.
