From now on, inside mathematical formulas, all brackets have to match and all big operators should admit well-specified scopes. To this effect, the way parenthesized expressions are edited has changed, although the old non-matching editing style can be restored using . Documents for previous versions of will be upgraded automatically in order to make all brackets match and determine the scopes of big operators. Although this task is accomplished using heuristics, the result should be correct most of the time. In any case, from the typesetting point of view, the upgraded documents will always look the same.