Prevent CRM from saving a record.

The OnSave event is fired when a user presses the Save or Save and Close button on the form. The event is fired whether the data in the form has been modified or not.

Validating data is a common reason to use the OnSave event. The OnSave event can cancel the save operation before it is sent back to the server. To cancel the save operation, the script should return false as shown in the following code.

event.returnValue = false;

The SDK helps in this situation. Look at the following page for more information. MSDN SDK: OnSave Event