The three files in the src/ subdirectory,
  tidy.h
  utf8.h
  utf8.c
are derived and modified from
HTML Tidy Library Project (http://tidy.sourceforge.net/).

    Copyright (c) 1998-2008 World Wide Web Consortium
    (Massachusetts Institute of Technology, European Research 
    Consortium for Informatics and Mathematics, Keio University).
    All Rights Reserved.