Itemupdating event handler
the actual Add / Update operation for which the Adding / Updating event is being fired).
Do NOT try to manually get the list item in code and update a property on it because the optimistic locking mechanism in Share Point may throw an error later on when the operation associated with the event to which you are responding attempts to complete.
You just have to check to see if the vti_sourcecontrolcheckedoutby property on the item was cleared: will not.
You can also use event receivers to validate the data that the user wants to change.
To prevent users from changing the name of the planet, you can develop a Item Updating event receiver.
This event occurs before the data is saved to the Share Point list.
Turning off the Require Check Out option is a great quick fix if you don’t require the item to be checked out in order for it to be edited.
But that option exists to be used, and some people really do need it.
Previously I worked as a Premier Field Engineer for Share Point @ Microsoft Belgium.Although asynchronous events expose a SPItem Event Properties parameter named properties just like their synchronous counterparts, remember that the operation has already completed so you cannot modify anything in the properties parameter (well, you can, but it doesn’t do anything).