A data processing device and a data processing method, a program and a program recording medium, a data recording medium, and a data structure, all enable data multiplexed into multiplexed data to be specified according to metadata irrespective of the number of pieces of data. A Clip( ) being metadata about a program stream into which a plurality of elementary streams are multiplexed includes as many stream_id/private_stream_id sets as the number of elementary streams number_of_streams. The stream_id/private_stream_id sets each consist of a stream_id, defined for each attribute of data in the MPEG-2 System (ISO/IEC 13818-1), for identifying data, and a private_stream_id for identifying data whose attribute is not defined in the MPEG-2 System. And each of the elementary streams multiplexed into the program stream is specified on the basis of the stream_id and the private_stream_id included in the Clip( ). Embodiments are applicable to, e.g., game machines using a DVD.