Scales are how you express how valuable a given criteria or rating is for you on this decision. It is the mechanism for getting the "apples and oranges" of most decisions mapped onto a common scoring system for evaluation.
Sixteen built-in scales handle the common cases like excellence or a high-best number. However it is easy to add custom scales so you can express the ratings in terms specific to the decision, an improvement over generic scales when communicating with others. Here we added a pages-per-minute (PPM) number scale and an ease-of-use word scale.