And just regular ol' autistic people with dysgraphia like me. Although I do relate to engineers and doctors a lot but I went the IT direction. I write using keyboards now.
It is dated now but green ink was the thing for a while since it couldn't be scanned. I would sometimes mark up a document that way if I wanted to just have a scratch copy for my own notes. Then when I was sure I could use red ink, scan it, and only the red was on the document.