Coding the ItemError event – PB Docs 2017

The ItemError event is triggered if there is a problem with the
data. By default, it rejects the data value and displays a message box.
You can write code for the ItemError event to do some other processing.
For example, you can set a code to accept the data value, or reject the
data value but allow focus to change.

For more information about the events of the DataWindow control,
see DataWindow Reference.