When using the pull-down entry function in Excel with the default settings, if you try to enter an item that is not in the list prepared for entry, an error message like the one shown below will appear and you will not be able to enter the item. In such a case, you can either allow any item to be entered, or display a message...

When using the sheet protection function, there is a function that allows detailed usage such as "allow selection and input in this range of cells, but not in other cells". For example, let's say you have a system that automatically creates transfer data when you enter a company name and amount of money as shown below. In this example...