A data field represents a single data item and is the only data element provided by the toolkit that has a value. Each one has a value instance variable for storing the value of the data item. Because the toolkit accesses data held in a data field using the field's name, the name for the data field name should be unique.
The com.ibm.btt.base.DataField class is the implementation provided by the toolkit. The toolkit uses the <field> tag to externalize data fields.