Index Rows - Idiot Proof Your Sheets!

What to do when some fool decides to <sort> a sheet just to see what happens?  

When creating a master sheet, inset a hidden column "Z_Row_Index.  Enter "1" in the first cell and then "2" in the cell below.  Highlight those two cells and drag the little widget at the bottom right of the lower cell.  This will drag-fill the line numbers downward.  If you change the master sheet (add, reorder or delete lines), of course you will need to renumber, but a small price to pay, IMHO.

If you need to restore order, just sort on the hidden column.  Ta da! 

Note:  Do not be tempted to use the <autonumber> function, it assigns a static number to the row and if you elide or add rows later, your numbering is out of sequence, which is useless.