bbcode v0.1

[bbcode]
[title="Hello World"]
[author="Anonymous"]

[main]
  [let="a"]5[/let]
  [while]a>0[do]
  [let="a"]a-1[/let]
  Hello, World!
  [val="a"]
  [/do]
  [/while]
  [call="test"]
[/main]

[test]
hihihi world!
[/test]

[/bbcode]

suggest and improve.

How about this
To define a tag you write [:hello].
Example

[:expert][b][u][o][][/o][/u][/b][/:]

[expert]I AM AN EXPERT PROGRAMMER[/expert]
You can explicity specify how many arguments a bbcode tag can have

[0:2br][br][br][/:]
So [2br] => [br][br]
[2br]wtf[/2br] produces an error by the parser/compiler.

For this to work, we need a good standard tag library.