An encoder for encoding data to generate corresponding encoded data including information indicative of a frequency, probability or range of one or more symbols to be represented in the encoded data. The encoder can include in the encoded data additional information indicative of whether information indicative of a frequency, probability or range for at least one symbol amongst the one or more symbols is in the encoded data. The encoder can include in the encoded data the additional information of whether information indicative of a frequency, probability or range for at least one symbol amongst the one or more symbols in the encoded data expressed as single availability bit information. The encoder can represent inclusion of information indicative of the frequency, probability or range information by use of a single availability bit value “7”, and non-inclusion of information indicative of the frequency, probability or range information by use of a single availability bit value “0”.
