In an authoring system of the invention, generation of volume configuration information for a DVD-Video is performed in parallel with generation of volume configuration information for a BD-ROM. Each of the client apparatuses 21 through 23 generates a piece of volume configuration information for a DVD-Video based on a user operation. Each of the client apparatuses 25 through 27 generates a piece of volume configuration information for a BD-ROM by obtaining a copy of an unfinished piece (a version 0.x) of volume configuration information for the DVD-Video and performing an editing processing on the copy. The piece of volume configuration information for the DVD-Video and the piece of volume configuration information for the BD-ROM have a format in common and each include a confirmation flag indicating, for each configuration element of the volume configuration information, whether the configuration element has been confirmed by the user.