The RAYLIST is a feature within ZEMAX which provides and easy way to visualize the propagation of any number of rays via the layout plots in ZEMAX (excluding the 2D Layout).  Rays may be defined one of two ways in the RAYLIST.TXT file:

• IMPLICITLY:  rays are defined by their normalized pupil coordinates, Px and Py
• EXPLICITLY:  rays are defined by their starting coordinates, direction cosines, a wavenumber

References

ZEMAX Optical Design Program User's Guide, ZEMAX Development Corporation