There is a protected period in a work.
The protected period exists in the work which authors, such as a book, a movie, and music, made fundamentally. As an intelligible example, the protected period exists in works which the celebrity made, such as music and a book. Generally the protected period is set as postmortem 50 years after an author makes a work, while it is alive. Moreover, the work of a movie is for 70 years. From the year of a day which died, the method of calculation of a protected period is deer calculated as it is good next year. Moreover, the system of war addition may be applied depending on the case. War addition is adding the days by the day before the San Francisco Peace Treaty's goes into effect from the day which acquired a usual protected period and copyright to the copyright acquired during World War II.