A method and apparatus for content substitution, consistent with certain embodiments of the present invention involves receiving data representing content, the data having at least first and second packet identifiers associated with first and second portions of content. The conference bridge comprises a spatialization unit for creating a spatial effect. During a playback mode of the test, the processor apparatus executes a playback algorithm stored in the ESC to cause the ESC to actuate the lamps in accordance with the stored data. According to the system of the invention, upon exception, a backup mode is determined according to the cause of the exception. The mixtures of particles obtained show electrochemical and mechanical properties that enable them to be advantageously used in electrochemical batteries and in paints. The pinhole permits direct offset illumination without the difficulty and expense of a conventional patch-cord assembly.