by Bob Puffer.
A scale is a series of comma-separated values, i.e., "lousy,poor,okay,good,smashing". 'lousy' is worth zero points because it holds that place in the scale, and 'smashing' is worth four points for the same reason.
Scales can be changed in two ways, directly in the table by editing the field values and by creating a new scale and assigning it to the grade item.
But... if grades are already awarded you can't change a four point scale into a three point scale because the '4' placeholder has already been awarded (fifth item in the scale).