[pixl97]

Yep, I call it the notepad/nano rule.

If I can open your file in a notepad and effectively edit it without the format changing or getting corrupted at saving its plain text.

Not plain text: Attempting to edit an .exe file in notepad.

Unfriendly plain text: Minimized javascript where the entire file exists on one line and the human readable elements jumbled together.

Plain text: Your average source code file/html file that attempts to adhere to something around 80-120 columns of text.