We have to be flexible about these just as we are about our birthing plans but it really helps to know what you hope for and lifts some of the weight of responsibility from the shoulders of your relatives or friends.
It covers things like where you would like to die, whether you want to be resuscitated in certain medical circumstances and can be very detailed about who you would like to have with you, music etc.
An advance decision to refuse treatment is only concerned with medical decisions. It must be discussed with and signed by your doctor. Then they can log your wishes centrally. In Oxfordshire we also need to complete the lilac form which is now done by your GP online and avoids CPR if you do not want this.