Most of the time, you will have a code number and use it to look up a combination. RAC is for the uncommon requirement that you have the combination to a lock or a key and wish to know what the actual code number would be for that combination.
RAC covers most automobile locks: About anything other than the high-security locks. Ford, GM, Chrysler, Toyota, Honda, BMW, Mercedes, Nissan, Hyundai, and so on. American, Japanese, British, German, Swedish, Italian, Korean.
When you run the program you are asked for the combination. You supply the cuts for the key, or the combination of the lock, and the program tells you the code number or numbers which will lead to that combination. If there are several codes leading to that combination, you are able to filter the list down to one or a few. There's no need to choose the code series or automobile first. The program will list all codes which lead to the combination that you requested.
You can also filter out code series that are out of date. And you can assign code series to a primary and secondary listing --- the primary one is the one you search each time, and the secondary one is for those autos that you seldom encounter.
RAC is a Windows program, requiring Windows 3.1 or higher.