One way to prevent unauthorised users from inserting a new row or column into a spreadsheet is to protect the worksheet. If you prefer to keep the sheet unprotected, input something into the last cell on the worksheet (cell IV65536). A single space is a good choice, since it's invisible. When the last cell is filled, Excel and 1-2-3 will not allow insertion of a new row or column. Instead, the programs will display a rather cryptic message that the casual user won't understand (but that savvy users will figure out).