Optics5 and Window5 share the function of  combining multilayer specular glazing assemblies using a simple ray tracing algorithm. They also share the SpecAve DLL described on this site. Optics5 allows new glazing types to be calculated from measured component data. Window5 performs a completer heat-transfer calculation of the window including glazing system and frame. Window6 is an extension of Window5 to complex light scattering and light redirecting glazing types. A much more complete description of these programs and how to download and update them is found on the WD software page. The VGS described here can be used to create complex "layers" for the CGDB and Window6.