A paraphrase of Asimov's first law of robotics: A program shall not harm a user's data or through inaction allow a user's data to come to harm. Every software engineer should take this to heart when designing a program. A user's data (or content) is sacred. Under no circumstances should it ever be lost -- especially due to a failure of the program.
My lifelong quest for playful programming and simple, reliable computing in all of its forms