Microsoft SharePoint 2013:Validation Settings
Validation Settings allows you to validate entries in each column of field in the library or list. You can define specific requirements for a column and when a user enters in it a value that does not meet this requirements a custom message will be displayed so that a user could change the value to the correct one. You can configure validation on the column level or o the list level. On the list level, you have the ability to compare column entries within this list. If you configure validation on the column level, you can compare column entry only with a static value.
Setting up validation for a list
- Navigate to the list for which you want to configure validation.
- Go to the List Settings page.
- On the list Settings go to Validation Settings.
- Enter =[Expires]>=[Created] to the Formula box in the Formula section.
- Specify a custom message for users.
- Click Save.
- Verify your validation settings by adding the item with incorrect value in the column.