Yes. You can enter your own text notations for each code and for each code reference.

For codes, these are called "code descriptions", and are entered at the bottom of the code list window. For code references, they're called "annotations", and are entered in the study window.

You can use code descriptions and annotations for any purpose. Typically, they serve as notes to yourself or to other researchers, or as extended descriptions to make it easier to understand what a code is used for.