Provided are a method to display a mark-up document according to a parental level, a method and an apparatus for reproducing AV data in an interactive mode, and a data storage medium. The data storage medium includes the AV data, and mark-up documents to reproduce the AV data in an interactive mode....http://www.google.de/patents/US7493552?utm_source=gb-gplus-sharePatent US7493552 - Method to display a mark-up document according to a parental level, method and apparatus to reproduce the mark-up document in an interactive mode, and a data storage medium therefor
