 For example take program A (new original code just written) and program B (a program licensed by a third party), the developer/licensor of A, who is also a legitimate holder or recipient of B may reproduce in A the needed code from B (e.g.the APIs or the needed data structures from program B) without copyright infringement and without authorization from the copyright holder of B.The licensor of A can do and distribute this without being bonded by conditions or limitations imposed by a licence of program B.