Capri interior codes consist of two letters. The first indicates the color, and the second indicates the material. Here are the color codes we've uncovered so far:

We've only decyphered one material code so far:

These tables are by no means comprehensive, and it's likely that the same codes apply to 1973 and 1974 models as well. At least some of the color codes for the 1976-77 Capri II are different.