Information recording medium, information recording device and method, information reproducing device and method, information recording/reproducing device and method, computer program for controlling recording or reproduction, and data structure including control signal

A computer program comprises an object data file for storing object for an ordinary reproduction and alternative reproduction, a playlist information file for storing playlist information prescribing a reproduction sequence of the ordinary reproduction and alternative playlist information prescribing a reproduction sequence of the alternative reproduction, and disk information file for storing sets of information containing (i) playlist specifying information for performing the ordinary reproduction, (ii) reproduction command information for specifying a command according to which the ordinary reproduction is executed, (iii) download instruction command information representing a command to be executed to download the object data delivered over an external network, and (iv) alternative playlist specifying information for performing the alternative reproduction during the download.