This area on your Illinois driver's license is used to indicate whether you have a living will. A living will is a legal document that allows you to make decisions about your medical care in advance, in case you are unable to communicate your wishes.
If you have a living will, you should carry a copy of it with you at all times, in case you are in an accident or become seriously ill. You can also indicate on your driver's license that you have a living will, by having the words "Living Will" printed in the Medical Information area.
By indicating that you have a living will, you can help ensure that your wishes are respected if you are unable to communicate them yourself.