This style sheet allows to transform a valid XHTML 1.0 (Transitional or Strict) (and probably also XHTML 1.1) in XHTML Basic. This transformation can imply some loss in the semantics context of the document and uses a set of HTML classes to identify some of the removed elements.
Note that nested tables are not allowed in XHTML Basic 1.1, so they'll be removed without further ado; so, if you intend to use this stylesheet for production use, you should first make sure the sources files don't have nested tables.
Please send any bug report to Dominique Hazaël-Massieux <dom@w3.org>.