Keys
Keys provide internal and external object identification. Keys are freely definable and the values for each key
type can be automatically generated if so desired. Keys may not only serve as identifiers, but may also
contain business logic with values, depending on the usage. The purpose of keys is also to be able to quickly
retrieve objects during data entry. One example of a key is the client’s account number. With the XXX Banking System you can have as many keys as you want, you can for example also store the client's
account number in your old banking system, in case it differs from the new one.