All input and output files in the QTL Cartographer system are plain text. They can be opened and viewed in any text editor or word processor. We suggest that you use a fixed-width font for viewing files. In addition, you should turn off automatic line-wrapping. Some of the output files produce tables of numbers: The fixed width font allows the numbers to line up in columns. Some of the tables are quite wide, and the line-wrapping destroys the columns. A good fixed width font available on most systems is Courier.