In Tinderbox, which is used to author these maps, notes can contain attributes. Some people use them to do fancy calculations, to manage spreadsheets, control their computer, or send their email. Since, I'm a scholar, I just like to put information in them about the books I read and when I need to return them to the University Library.
To see an example of how I use attributes, look at the Bibliography entry for Edward Tufte's classic book on information design, Visual Explanations.
To see an example of how I use attributes, look at the Bibliography entry for Edward Tufte's classic book on information design, Visual Explanations.