Most of us have a to-do list. For years I kept mine in a hardcover lab notebook, copying items forward at the start of each day until they were done or I had given up on them.

After my last crash, I started keeping a to-don’t list as well—a list of things that I’m not going to work on because there isn’t time to do everything. The first few lines look like this:

I will not work on: until I finish:
Merely Useful The Tidynomicon
Software Tools in JavaScript JavaScript versus Data Science
Software Engineering: An Evidence-Based Approach Analyze That!
Sex and Drugs and Guns and Code The Cloudherd and the Tiger's Boy

When I finish something in the second column, I’m allowed to promote something from the first, except I almost never do: over the past three years, something more pressing has almost always come up. Occasionally, in my weak moments, I create a fresh GitHub repository for one of my to-don’t projects, but that’s as far as I let myself go.

I don’t know how useful a to-don’t list would be for other people, but it has helped me. I think it would help volunteer groups and software projects and research teams as well, just like lists of topics that are not to be brought up at the dinner table help keep family gatherings friendly.