OptionalarrayEvaluate each cell of the range as an array-entered formula whose extent is that one cell.
This is how a conditional-format or data-validation formula is evaluated. Nothing
implicitly intersects — a range reads as the whole array wherever it appears — and each
cell keeps the top-left value of its own result, the way an array-entered formula fits its
result to its extent. So $J$1:$J$9="x" answers J1="x" in every cell, while
SUM(IF($J$1:$J$9="x",1,0))>1 still sums the whole array. A relative range moves with the
cell, so $J1:$J9="x" answers each row's own J cell.
By default a cell whose result is an array spills, as a formula filled across the range would.
Options for ICellRange.addWatch.