Many brands of guitar potentiometers are stamped with either a ‘B’ for “Linear Taper”, widely used for tone controls, or ‘A’ for “Audio Taper”, generally used for volume controls.
So of course, CTS has to be different! 🙂 They use an alpha-numeric code system to designate the specifications of their guitar pots.
I found this chart to be very helpful when ordering pots for guitars. Often, even the vendors don’t understand what they’re selling! On more than one occastion, I’ve ordered potentiometers of one type (linear or audio taper) and received the other type.
With this chart, I can check the numbers from the photos in the ads and be sure of what I’m buying (so long as they have the right photo!)