When a user works data required for allowance for the use thereof, the work
processing is carried out by utilizing an exclusive work processing
device. Thereafter, only the data of work information indicating what kind
of working has been made to the original data (for example, differential
static image data indicating a difference between the original static
image required for allowance for the use and the static image after having
been worked) is stored, whereby the use without permission of the data is
prevented.
