A data structure having at least content data and reproduction control information with which reproduction of the content data is controlled is disclosed. The data structure includes an index table, an object, a play list, and clip information. With the index table, reproduction of content data is managed. The object is called to the index table and represents a method of reproducing at least the content data. The play list is called from the object. The clip information is called based on the play list and represents attribute information of at least the content data. At least the index table, the play list, and the clip information each are capable of containing extension data. The extension data contain main identification information and sub identification information as identification information which identities the extension data.