A buffer note is a note that is like a specific container of notes that you will use later. They buffer the gap between note production and assignment of notes to projects. I came up with these kind of notes when I had written a couple of books but still wrote more about the same topic and was sure that I would be making a second edition.
The second edition of the Zettelkasten Method Book is a perfect example. After I was done with the draft of the first edition of the book, I continued to add notes on this topic to my archive regularly. If I incorporate all the new notes into the book while editing it, I would never be able to finish. Or: If I just incorporate the new notes in the structure note on the Zettelkasten Method, I would never be able to find all the new notes that are not already used in the book. It would be a mess.
Therefore, I made a note in which I copied the title (+ID) of the new notes I have written that were not used in the book. I used a simple convention: ID + title + some context. The context made sure that I would know later on why I thought that the particular note could be used for the book. This is a (translated) example:
[[201708051151 False feedback for men in modern world]] What are the feedback problems of the Zettelkasten Method? Is there a real danger that people would write notes only for the sake of it?
The note is about problems like midlife-crisis, boyhood crisis, and similar stuff that emerges because of false feedback (e.g. thinking that a career serves as the pinnacle of meaning in life). I intended to use some of the thoughts to illustrate how you can get lost in knowledge work. Other examples are: Over-crafting the tools, over-digitalization (not reading real books) etc.
The same can be applied to new writing projects. I have a couple dozens of books that I am writing. New notes can be linked very fast to multiple books notes (either outlines or buffer notes) and with every note more than one book is growing. Like this, you can effectively
write quite a lot books at the same time without losing the overview.
The buffer notes’s role for the Zettelkasten Method is really a means to store notes relevant to a project in a rather unstructured manner.
Update 2018-03-06: The term “buffer note” appears to be a weird choice, native English website readers tell us in the forums. We consider changing the term in the future. Chime in if you have something you want to add.