The "Restrict deletion" rule prevents a row from being deleted if it corresponds with data elsewhere in the database. For example, if a transaction refers to a customer, the customer cannot be deleted from the customer table in a way similar to a Primary Key.
Where - the WHERE clause that creates the lookup for the condition
Where Builder - opens the WHERE Builderdialog to create your WHERE clause using a GUI interface
Message - the "condition not met" message to display for the user
Succeed | Fail - determines if the message is displayed if the condition Succeeds or Fails
[Add/Modify | Delete] - determines if the Rule is checked when a row is Added or an existing row is Modified, or if an existing row is Deleted
