Adding Data Entry Instructions with Input Messages

We've seen that Error Alerts tell the user if they've violated a data validation, and what they've done wrong. Input messages tell the user what sort of data is permitted in cells before the data is entered.

To demonstrate how this works:

1. Select that same range of cells with which you've been working.
2. Click Data Validation Input Message. You'll see:
   

   Figure 2–48. Delivering the message: The Input Message dialog box.

3. Type Two-character limit in the Title field and “You must enter exactly two characters in this cell” in the Input Message field, and click OK.
4. Click in any cell in the selected range; you'll see:
   

   Figure 2–49. Proactive prompt: an input message

The idea is to pre-empt possible data entry mistakes, by letting the user know in advance what's allowed in the cells.