As a programmer has obtained the consent of the copyright holder and created another work that results from the modification or other means of the copyright holder’s original work, such resulted work becomes the derivative work of the original. In general, the Copyright Law grants derivative works protection equal to that of original works. Therefore when the derivative work becomes the subject of a third party’s modification, this third party has to obtain first the consent of both the copyright holder of the original work and that of the derivative work. If the modification is performed on a work derived from a free software program, it involves not just the consent of the original copyright holder. As the derivative work enjoys independent protection from the Copyright Law, the original copyright holder usually imposes certain restrictions on derivative works in the licensing terms. For example, the original copyright holder may require the derivative works to adopt the same licensing terms that the original work adopts or to open the source code, so as to ensure the practice of free software is continued and the code freely circulated.