Polarimetric saccharimeters are instruments which measure the relationship between the optical rotation caused by an aqueous solution of a sample and that caused by a pure sucrose solution of prescribed concentration, using the same polarized light. This Recommendation applies to polarimetric saccharimeters that are graduated in sugar degrees (!Z) in accordance with the ICUMSA International Sugar Scale (see Annex A) and that belong to the visual or photo-electric type, including: a) saccharimeters with a rotating polarizer or analyser of which the angle of rotation can be measured and which are illuminated by a monochromatic light source of known wavelength which must be between 540 nm and 633 nm; b) saccharimeters with quartz wedge compensation and illuminated either by a monochromatic light source of known wavelength which must be between 540 nm and 633 nm, or by the light of an incandescent lamp filtered in such a way that the distribution of the spectral energy from the lamp, arising from the degree of spectral filtration by the filter and from the spectral sensitivity of the detector (eye or photo-multiplier), permits the use of radiation of effective wavelength 587 nm; c) saccharimeters which operate according to a principle of measurement other than those given in (a) and (b).