1. This rule is designed specifically for finance and business calculations. Whilst most of the scales on this rule are standard scales, but with different naming, it does have a few scales that are not standard.
2. The C and CF scales are the same as the C and CF on "standard" rules. The R and RF are the equivalent to the D and DF scales on  "standard" rules. These scales lend themselves to problems of multiplication, division and proportions.
3. In this case C stands for Cost and R for Retail.
4. Two scales which are different are the C% (cost mark-up percent) and R% (retail mark-up percent). These special scales, C% and R%, are unusual in that they run from 0 to 9, they are in effect the values of the C and CI scales minus 1. The picture shown as "use for mark-up" is an example of the C, R and C% scales. With the retail price of 15 (R scale) and the cost price of 12 (C scale)  the cost mark-up is 25% (C% scale) . The picture shown as "use for discount" is an example of the C, R, and R% scales. With a retail price of 75 (R scale) and a cost price of 60 (C scale) the discount is 20% (R% scale).
5. On the back of the rule are three log-log scales for compound interest problems. To cover as wide a range of scales as possible these log-log scales are to the base 10, rather than the more common e (2.718). The lowest value of 1.00232 this is equivalent to a daily rate when the annual rate of interest is 2.3% and enables interest on a daily basis.