quadrat°

"I've put in what seems to be necessary to fix the current column of the current alignment. Try to go on, since this might almost work."

"I can't figure out why you would want to use a tab mark or \cr or \span just now. If something like a right brace up above has ended a previous alignment prematurely, you're probably due for more error messages, and you might try typing `S' now just to see what is salvageable."