MARC21       007s'04  Configuration of playback channels
     Values: 
              a   Acoustic [obs.]
              f   Monaural (digital) [obs.]
              g   Quadraphonic (digital) [obs.]
              j   Stereophonic (digital) [obs.]
              k   Other (digital) [obs.]
              m   Monaural
              o   Other (electric) [obs.]
              q   Quadraphonic
              s   Stereophonic
              u   Unknown
              z   Other