1. USABILITY Usability is a measure of how well the software supports the execution of user tasks. Key factors contributing to usability are the presentation of information and the management of user interaction. Usability includes two other measures, affordance and accessibility. 1.1 Affordance is a measure of the cost of learning to be productive with a user interface [Nor]. A user interface may be highly usable once it has been learned, but difficult to learn. The well-known EMACS text editor...