Validates child controls that are directly hosted within the container. Does not validate any of the children of these children. For example, if you have a System.Windows.Forms.Form that contains a custom System.Windows.Forms.UserControl, and the System.Windows.Forms.UserControl contains a System.Windows.Forms.Button, using ValidationConstraints.ImmediateChildren will cause the Control.Validating event of the System.Windows.Forms.UserControl to occur, but not the Control.Validating event of the System.Windows.Forms.Button.