Exactly. I also use those colors.

I made a little system where blue diagrams are services I need to code and host like a nodejs server

green is stuff I need to host only like nginx, but no coding

red is external infra I can't control at all, like Anthropic's API.

And then I make drawings of how I connect them and in the end I just generate the code, so I go from pen and paper to claude code.

I spent an unreasonable amount of time recently thinking about how to color- (and symbol-) code my notes. I wanted to create a simple generally applicable system that I can use for any project.

For thinking, nothing beats handwriting. It's just the unconstrained freedom of movement in every direction, shape or form, and the lack of friction and distractions.

But then you sometime also want to organize or share stuff, so that's where digital comes in. I have an automation that takes a photo of my notes with my phone, uploads it to Obsidian, and OCRs it into markdown and tags it, so I basically end up with a "symbolic" 1-1 equivalent of analog handwriting + digital text

My system still evolves, but what I currently use is:

Color: - black = just "normal" text - red = critical/"must" - yellow = important/"should" - green = highlighted/"could"

Symbols: - bulletpoint [ ] task -> reminder

I also do brackets and underlines which translate to # heading1 and ## heading2 in markdown

I write by hand with a fountain pen with black ink + use 3 fineliners and small colored sticky flags.

Some observations: - yellow is not great on white paper due to bad contrast; it also rarely comes as ballpoint, but fineliner options are available - blue and green are visually very similar, to the point of kinda being redundant - for sharing with other people, the system must be as generally understandable as possible. Here the traffic norms such as ISO 7010 (https://en.wikipedia.org/wiki/ISO_7010) could be considered - also there's the aspect of accessibility, with a relevant portion of population being colorblind - The simplest most effective system seems to be: one main color (black or blue) and one highlight color (red I think works best), plus a couple of symbols such as bullet point, task, reminder that translate well into markdown