Well, I know this says it's documenting
undocumented bbcode, but I figure I'll just do a basic "what is" on each one and some basic syntax.
Be sure that you "nest" your bbcode properly; an example:
GOOD:
[b][i][u]This will have multiple elements.[/u][/i][/b]
BAD:
[b][i][u]This will have multiple elements.[/b][/i][/u]
You need to terminate the tag as it is called, in the closest order.