You can also use event receivers to validate the data that the user wants to change.
This walkthrough is based on the first one where I have a custom list with planets of our solar system.
For more information, see Script Exploits Overview.
event when an Update button (a button with its Command Name property set to "Update") within the control is clicked, but before the Form View control updates the record.
Users can change data like the number of moons or the distance to the earth, but they are not able to change the name of the planet.