A variable-length encoding apparatus receives image data on a block basis, generates a plurality of syntax elements from the image data, and outputs an encoded stream by performing variable-length encoding of the syntax elements. The first module includes a linear feedback shift register and a permutator circuit. A polymer made of this oligophosphazene compound exhibits high transparency and a high refractive index and is also less likely to cause optical dispersion, and thus it can be used as an optical lens, a retardation film, a light transmission body and other optical moldings. The present invention facilitates a more directed effort to investigate leads and makes the information of customers available for follow-up that has higher prospective sales potential.