The reference comprises a collection of areas. They are entered in curved brackets, separated by a semi-colon. While the row and column parameters remain the same, the last parameter refers to which of the grouped areas you would like to use for your current search.
The sequence in the reference is key here: The area you enter first is also number 1. The areas are counted from left to right – regardless of where the area is located in the worksheet. If you’d like to display the value in another array, you only need to change the area in the last parameter. If this parameter is left out, Excel automatically assumes you mean the first area.
Lastly, INDEX can also be used as a matrix formula. Here, a selected area that contains multiple cells is reproduced in just as many cells. A row or column can be displayed as follows: First, select the corresponding number of empty cells and then enter the INDEX function as normal. (The area has to remain highlighted!) Instead of confirming the entry using the [Enter] key, use the key combination [Ctrl] + [Shift] + [Enter]. The selected area will now appear at the desired position in the table.