A more thorough explanation:

A physician's directive is a legal document that explains a person's wishes about medical treatment if they become unable to communicate or make decisions for themselves. It is also known as an advance directive or medical directive.

There are two types of physician's directives:

1. Power of Attorney for Healthcare: This document designates a surrogate decision-maker for healthcare matters. It takes effect upon one's incompetency and ceases to be effective once the person regains their capacity. The agent must make decisions in accordance with the person's relevant instructions, if there are any, or in their best interests.
2. Do-Not-Resuscitate Order: This document instructs healthcare providers not to perform cardiopulmonary resuscitation (CPR) if the person's heart stops or they stop breathing. It is typically used by people with terminal illnesses or those who do not wish to be resuscitated if their heart stops.

For example, if a person has a power of attorney for healthcare and becomes incapacitated, their designated agent can make medical decisions on their behalf. This can include decisions about life-sustaining treatments, such as whether to continue or withdraw life support.

Another example is if a person has a do-not-resuscitate order in place and experiences cardiac arrest, healthcare providers will not perform CPR, as per the person's wishes.