It was designed with the following goals in mind.

Liberal input:
    Any input should be able to be accepted and handled in a reasonable an predicable manner.

Strict output:
    All output can be valid XHTML (including properly nested output). Output must be consistent and semantically correct (no line breaks when we really want new paragraphs)

Small learning curve:
    It is as compatible with BBCode as possible, except where it would violate the above requirements. Certain aspects of BBCode are simply broken, they are intentionally dropped.

Extensible:
    It is possible to create new tags or modify current ones with relatively little effort. It does take some programming knowledge though.

At the moment there are two libraries for this language: PHP and Python. We plan to have a compatible Javascript library available in the not too distant future. Also support for output in other markup languages is planned.