It allows the design of the instrument to be defined as a series of parts separated by drift spaces, and the parts can be placed off-axis.
Parts can be rotationally symmetric lenses, deflectors, multi-poles, or sector magnets.
These models describe the relation input output coordinates of a ray. The optical properties of the design are determined by shooting rays through the system, fitting to the end positions the coefficients of a transfer function, from which properties are calculated like probe current and probe size. Graphs can be generated displaying the dependency of a property of the design as function of a design parameter. A tolerance analysis can show the influence on properties of parameters varying within user-defined tolerances. On-line help is available on how to use the program and how to interpret the results.