Ask HN: How do you use Zettelkasten for mathematics and CS?

Given the recent HN trend of Zettelkasten, I thought I’d ask how do you actually apply the methodology when writing down notes from hard sciences.

I’m not that interested in implementation details (which is what is discussed on HN most of the time), but rather:

1. what do consider one page

2. what do you link

3. what metadata do you add

I also have some problems with general note-taking (in Analysis): one of the problems I have is that I’m not sure whether it’d be better to rewrite the definitions, theorems, and proofs verbatim and add some personal notes to them, or whether to just have the personal notes and not copy the facts from the book.