The impurity line and continuum emission for ITER reference H-mode and ITB were modelled using the SANCO impurity transport code. Using the instrument sensitivity for a spatially resolving crystal spectrometer array with doubly-curved crystals and 2-D detectors, signals and signal-tonoise ratios were calculated for impurities including argon iron and krypton. These were shown to have lines suitable for the measurement of the ion temperature (0.5-30keV) and the rotation over almost the entire plasma minor radius. The main contribution to the signal-to-noise is the plasma continuum radiation on which the lines are superimposed. The main limitation to allowed impurity concentration is not the contribution to Zeff, but the impurity radiated power, there being a broad operating range between about 100 kW and 10 MW. The spectrometer array has now been integrated into the ITER design.