This chapter is really not recommended for newbies. It demonstrates how to do strange things with txt2tags filters, abusing of complex patterns and Regular Expressions.
BEWARE! The following procedures are NOT encouraged and can break things. Even some text from the document source can be lost on the conversion process, not appearing on the target document. Just use these tactics if you really need them and know what you are doing.
Note: Filters are a powerful feature, but can be dangerous!
Note: Bad filters do generate unexpected results.
Keep that in mind, please.