I have a 6 x 9 spiral notebook with a rather attractive multicolored cover which I pressed into service as an address book many years ago. Many, many years ago. This is my personal address book featuring friends, family and acquaintances, all people whom I thought enough of to preserve their addresses for quick and easy access. (Yes, it is more efficient than digital address books. Not open to debate.)
As time passed, I found myself marking various names thusly: /DEC, sometimes followed by a date. In this manner I have kept track of those close f, f, and a who have preceded me in death. I was addressing an envelope a few days ago, and on a whim I thumbed through the pages and counted the /DEC notations. 41 names so marked. 41 people I cared enough about to enter in my collection of personal friends.
Mortality: It's for everyone!