Basically, it’s Cal Newport’s system plus a checklist of “input streams”: e-mail, texts, scratch paper (I use sticky notes to force myself to be concise- and they’re really handy to keep in my back pocket anyway), mail, RAM dump. Level 2 is hopefully going to somehow incorporate filing systems, a separate to-do list for optional tasks, and checklists for adherence to recurring tasks (scheduled daily, weekly, monthly). I think this means scheduling a bigger OS session on a non-workday. Level 3 will hopefully organize creative overflow. (Possibly scientific hacking endeavors? We’ll see, that might be level 4.)
Level 0 is still just the cynical philosophy “If it didn’t get done, and I’m still alive, it must not have mattered enough to remember it.” The opposite of perfectionism, it’s meant to apply to extreme environments, like heavy depressive swings or unusual danger (an active amygdala has a way of focusing the mind).