An application-specific client for object-oriented processing of markup includes a model object and a plurality of element objects. In one aspect, a diffractive optical element is made by forming a multilayer structure comprising multiple amorphous silicon phase shift layers having respective thicknesses selected so that the diffractive optical element is operable to phase shift infrared light within an operative wavelength range. The selected element is highlighted in the representation and the highlighting can be propagated to any other elements related by the mapping that are displayed in the representation. The system includes a controller communicably coupled to the rotation sensor.