A more thorough explanation:

A written directive is a legal document that outlines a person's wishes regarding medical treatment if they become unable to communicate or make decisions for themselves. There are two types of written directives:

An advance directive is a document that designates a surrogate decision-maker for healthcare matters in case the person becomes incompetent. The power of attorney for healthcare must be in writing and signed by the principal. The agent must make decisions in accordance with the principal's relevant instructions, if there are any, or in the principal's best interests.

Example: A person creates an advance directive that designates their spouse as their healthcare proxy in case they become unable to make decisions for themselves due to a medical condition.

A do-not-resuscitate order is a written directive that instructs healthcare providers not to perform cardiopulmonary resuscitation (CPR) if the person's heart stops or they stop breathing. This order is usually given when the person is terminally ill or has a medical condition that makes resuscitation unlikely to be successful.

Example: A person with a terminal illness creates a do-not-resuscitate order that instructs healthcare providers not to perform CPR if their heart stops or they stop breathing.

These examples illustrate how a written directive can help ensure that a person's wishes regarding medical treatment are respected even if they become unable to communicate or make decisions for themselves.