The BSDF Data Interchange file format was developed by Radiant Imaging, Inc (RI).  It is designed to be a compact, simple way to transfer BSDF data.  Specifically, as the Imaging Sphere for Scatter and Appearance (IS-SA) developed by Radiant Imaging can provide a full hemisphere of BSDF data in a single measurement, there is a need to export this data for straightforward use in a lighting design and analysis software program, such as ZEMAX. This file format is employed by the user-defined scattering function RI_BSDF.DLL which is provided with the ZEMAX installation. This DLL uses the BSDF data provided in the input file to generate a scattering distribution, which may be applied to any non-sequential surface in ZEMAX.