Today I had to delete everything before a current line. So … in VI, I marked that line with the command ‘ma’ (mark this line and assign it to the letter ‘a’), then went to the first line with ‘:0’. Typed ‘d’ for delete, then entered the command ‘`a’ (that’s a backtick, below the tilde ~) to move to the line I just assigned the letter a to, and everything between the current line I was on and the position at ‘a’ was deleted.
I was surprised it worked, so I felt the urge to post it here. haha