zeisstopnm --version (return code: 0)
zeisstopnm: Using libpbm from Netpbm Version: Netpbm 10.0
zeisstopnm: BSD defined
zeisstopnm: RGB_ENV='RGBDEF'
zeisstopnm: RGBENV= 'RGBDEF' (env vbl is unset)
zeisstopnm -h (return code: 1)
usage: zeisstopnm [-pgm|-ppm] [Zeissfile]