does not use the
      preset dictionary feature, the compressor must not set the FDICT
      flag.

      A compliant decompressor must check CMF, FLG, and ADLER32, and
      provide an error indication if any of these have incorrect values.
      A compliant decompressor must give an error indication if CM is
      not one of the values defined in this specification (only the
      value 8 is permitted in this version), since another value could
      indicate the presence of new features that would cause