Data Validation
Don't miss how easy it is to restrict entries in an Excel column or row to a pre-specified list.
On a separate worksheet, enter a list of values.
Select the range in which you want to control which entries can be made, and then on the Data tab, select the Data Validation drop down menu, select Data Validation.
On the 'Settings' tab choose 'List' in the Validation Criteria menu. Then in the Source box, choose the range which contains the pre-specified list.
You can choose to have a dropdown menu listing the choices.
On the 'Input Message' tab enter a note you want the user to see when he or she selects the cell in which data is to be entered.
On the 'Error Alert' tab you designate a message to send the user when one of the pre-specified choices is not used.