When it comes to driving licences, there are different types that serve different purposes. For instance, if you spot a green ADI badge on someone's licence, it means that they are a fully qualified driving instructor who has passed all the exams required to teach and coach pupils. On the other hand, if you see a pink trainee licence, it means that the person is still in the process of qualifying as a driving instructor and is learning while earning money. It's important to note that trainee licence holders should not over-commit to too many pupils, as the licence is designed to help them gain experience and cover everyday costs, rather than as a means of earning money.