I searched for discussion on this & couldn't find any, so forgive me if I'm repeating it.
Sectional & other views can be broken either vertically or horizontally by selecting their crop boundary & clicking on the break symbols. At first, the break symbols appear on all edges of the view boundary. But once you make one selection (say, a horizontal break), it appears to be impossible to break the view in the other direction (in this case, vertically). I have a section that I need to compact both vertically and horizontally to fit it onto the sheet. Is this a Known Problem, or am I missing something?