The parts are built from fully parameterized sequences of geometry instructions. For example, you can load the slab_waveguide_straight part into a model and then specify the core and cladding widths, the element length, and the core offset. Wave Optics parts include selections for the core and the cladding domains that can be used when defining the material properties. Furthermore, there are also other selections defined for setting up ports and other boundary conditions and to simplify the definition of the mesh sequences.