In writing the book, I created a font to represent logical operators on two variables using Fontographer. The complete set of "jots" can be found on page 83.For those interested, the font and the file used to create the font are provided here. You can install the font by copying the font file into your Windows/Fonts directory if you have a windows machine. If you want to modify the font, or add to it, feel free to use the fontographer file