Coded Aperture System performances are defined by the geometry of the code, detector pixel geometry relationship and focal length. Physical Coded Aperture Systems deviate from the ideal ones on two basic aspects: uncertainties on pixel location and size coming form the manufacturing process and deviations from their theoretical transparency/opacity values (1/0, 0/1), when support structures are required. Mask support structure imposes penalties on transparency as a function of the energy and angle of the incident photons. Pixel position and size values include uncertainties coming from the code cut in tungsten plates and assembly process. The scope of this paper is to summarize the results of the code elements position and size, as well as transparency/opacity values found for the IBIS Coded Aperture System. Both sets of data define the optical performances of the IBIS Mask required to perform accurate imaging of celestial gamma-ray sources.