Code, and programming-like talk. "functions" and "variables" and "pointers", stuff like that. It just lets you know what they're doing, and a lot of the time you don't have to see their code to help them fix issues. Like, yesterday, I found a game breaking glitch in someone's patch, and I knew what was causing it when I reported it and was more help than the average Joe when it came to reporting it, or so I'd like to think.