The 6.4.3 release of the Oslo lens design software from Lambda Research Corp. features 18 modifications that increase flexibility and customization options. An added command transfers any Oslo plot or graphic to the Microsoft Windows clipboard as a bitmap. The modulation transfer function, which analyzes both X- and Y-field data points, allows users to model general anamorphic surface shapes without the control problems usually associated with spline surfaces. In addition, the software recognizes whether multiple interferometer files contain wavefront, surface or filter data and provides feedback regarding the source and type of errors added to optical surfaces in a design. It also enables the performance of complex tolerance modeling to predict as-built optical system performance.