The default behavior of the MForm controls tree is to display one validator for all MForm controls. This validator can be displayed before or after the MForm content, but it does not provide a way to display the error near the field.

There is however an Addition control that can attach error displaying to the field. This Addition is called ErrorLabelAddition. This control creates an extra span near the field. On the client side, the object corresponding to this addition plugs into the item's constraint events. These events are fired every time the constraint is checked and returns either positive or negative result.