Recording data has content data and navigation control data to enable a legitimate player to navigate the content data. The recording data has a content data set and a spurious data set that is difficult to distinguish from the content data set but will ignored by a legitimate player. The content data is associated with the content data set and the spurious data set. The spurious data set may be associated with control data that inhibit playing or correct playing of the content data. A ghost structure such as a ghost video title set my be provided by causing information in at least one of the video title set information, video manager information and the volume information file structure to reference a non-existent video title set or not reference an existing video title set. The recording medium may be an optical disc such as a DVD or its precursors.