DATAFIELD is in context in a NAME condition ON-unit (or any of
its dynamic descendants). It returns a character string whose value
is the contents of the field that raised the condition. It is also
in context in an ON-unit (or any of its dynamic descendants) for an
ERROR or FINISH condition raised as part of the implicit action for
the NAME condition.
>>-DATAFIELD-+----+-------------------------------------------->< '-()-'
If the string that raised the condition contains DBCS identifiers, GRAPHIC data, or mixed character data, DATAFIELD returns a mixed character string.
If DATAFIELD is used out of context, a null string is returned.