Defining informational messages, error messages & warning messages 
The gadget spec URL could not be found

In the last section, we learned to perform validations on the input form fields. In this section, we will learn how to configure messages to notify the users whether the data entered by them fails the validation. The "Data Validation" dialog box has three tabs.
  • "Settings" for adding validations
  • "Input Message" for configuring input message (hints for the user). This input message will be displayed when a cell is selected. 
  • "Error Alert" for configuring informational, warning and error messages. These messages will be used to notify the user whether the data fails validation. 

Input Message
Select the "Input Message" tab in the "Data Validation" dialog box.
Enter the message that is to be displayed as user hint in the "Input Message" text field.

 Error Alerts
Select the "Error Alert" tab.
Choose a style: Stop, Warning or Information.

What purpose does this serve?

It prevents the user from submitting the data in the form. Only after all the errors are corrected, the data will be submitted. "Stop" must be used with mandatory fields.

It allows the user to submit the data, but a warning message will be displayed. "Warning" could be used with optional fields.

Enter the message that is to be displayed in the "Error Message" text field.