The easiest and most simple approach to understanding a PSN is to use the wallet card. If you take the card and fold it in half you'll see that the front directs a reader "in case of emergency" to "look inside". It bears the internationally acknowledged emblem signifying to first responders that this is serious stuff. On the backside the card gives a place for you to write your name and contact information.
We suggest that you complete only those sections that you are comfortable with, knowing that emergency personnel and others will have access to whatever is on this card. Only you, however, will know how comfortable you feel with balancing potential emergency needs with privacy.
Inside the card are spaces for you to write the names and contact info for the three (that's right: THREE) people who you authorize to speak on your behalf if you cannot speak for yourself. Here you can add your allergies, and information on your insurance and on your primary care provider.