Up
current = Up(current);
current = Up(current);
if (Up(current) == (ITEM *)0) {
current = Up(current);
Up(i) = r ? IthItem(m, n-Cols(m)) : (ITEM *) NULL;
Up(IthItem(m, n)) = IthItem(m, Nitems(m)-1);
Up(IthItem(m, n)) = IthItem(m, up);
Up(i) = r ? IthItem(m, n-1) : (ITEM *) NULL;
Up(IthItem(m, n)) = IthItem(m, n-1);
Up(IthItem(m, n)) = IthItem(m, up);