HI,
This is a "legal" question.
Imagine i take one example from "Qt Examples":
Qt Code: 
  1. /****************************************************************************
  2. **
  3. ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
  4. ** Contact: Nokia Corporation (qt-info@nokia.com)
  5. **
  6. ** This file is part of the examples of the Qt Toolkit.
  7. **
  8. ** $QT_BEGIN_LICENSE:LGPL$
  9. ** Commercial Usage
  10. ** Licensees holding valid Qt Commercial licenses may use this file in
  11. ** accordance with the Qt Commercial License Agreement provided with the
  12. ** Software or, alternatively, in accordance with the terms contained in
  13. ** a written agreement between you and Nokia.
  14. **
  15. ** GNU Lesser General Public License Usage
  16. ** Alternatively, this file may be used under the terms of the GNU Lesser
  17. ** General Public License version 2.1 as published by the Free Software
  18. ** Foundation and appearing in the file LICENSE.LGPL included in the
  19. ** packaging of this file.  Please review the following information to
  20. ** ensure the GNU Lesser General Public License version 2.1 requirements
  21. ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
  22. **
  23. ** In addition, as a special exception, Nokia gives you certain
  24. ** additional rights. These rights are described in the Nokia Qt LGPL
  25. ** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
  26. ** package.
  27. **
  28. ** GNU General Public License Usage
  29. ** Alternatively, this file may be used under the terms of the GNU
  30. ** General Public License version 3.0 as published by the Free Software
  31. ** Foundation and appearing in the file LICENSE.GPL included in the
  32. ** packaging of this file.  Please review the following information to
  33. ** ensure the GNU General Public License version 3.0 requirements will be
  34. ** met: http://www.gnu.org/copyleft/gpl.html.
  35. **
  36. ** If you are unsure which license is appropriate for your use, please
  37. ** contact the sales department at http://www.qtsoftware.com/contact.
  38. ** $QT_END_LICENSE$
  39. **
  40. ****************************************************************************/
  41. ...
  42. ...
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According to the GNU General Public License version 3.0 and freedom number four i can change this code and share the changes. Right?

The only restriction would be to make it also under the GPL Licence.

Can someone give me an example of a compact header to use for this purpose.

On the other hand, tell me please if i am reading this worng.

Thanks