Assembly: Microsoft.SharePoint (in Microsoft.SharePoint.dll)
If the field is being rendered on a New item form and has not yet been set, the default value for the field type is returned.
When the BaseFieldControl first loads and when it reloads after a postback, Value is given the same value as . If the field has never been set for the current list item, is a default value for the field type.Notes to inheritors
If the value of the field is to be changeable by users, your logic should change Value directly and then call UpdateFieldValueInItem, which will set to match Value and ensure that the appropriate value-changed event occurs. Neither UpdateFieldValueInItem nor the set accessor of directly performs any validation of the data. Consider calling Validate after setting Value and then checking the value of IsValid (which should be set by Validate) before the call to UpdateFieldValueInItem.