Somebody wrote “add more garlic” in the margin of the family recipe. That’s one person’s opinion living three generations on.

Notes in a margin are opinions that outlived the people who held them. Somebody disagreed with the recipe, wrote it down, and now three generations cook it their way without ever having met them, which is a strange and quite nice form of continuing to be around. Permanence is rarely planned. It is usually an afterthought in pencil.

Write in your copies of things. Add the correction, the date, the reason it went wrong the first time. Someone will be glad of it long after you have forgotten writing it.