Here's an explanation of each one: https://askubuntu.com/questions/926461/whats-the-difference-between-the-magic-reisub-reset-and-holding-down-the-power https:

Here's an explanation of each one: https://askubuntu.com/questions/926461/whats-the-difference-between-the-magic-reisub-reset-and-holding-down-the-power https://askubuntu.com/questions/926461/whats-the-difference-... Basically "E" and "S" were an attempt to save as much data as possible and "R" may not be needed (but including it created the word "busier" backwards). I'm guessing "I" may have been to be sure "U" wouldn't get stuck somehow, but don't really know.