If the DR900 is specified to have a measurement range of 0-2 Abs, why is it able to read higher than 2.0 Abs in single-wavelength and user-program modes?
Measurement range DR900
The specification relates to an Abs range that will give linear response across multiple instruments. The majority of the calibrations stored on the DR900 do not go higher than 1.5 Abs, but on a given instrument, higher values are possible. They will not be linear much above 2.0 Abs however.