Use DataSetField, in conjunction with the XMLBroker property, to identify the XML dataset that the TXMLDataSet object represents. If the dataset is the dataset represented directly by the XML broker's data packet, DataSetField is an empty string and the XMLBroker property fully describes the dataset. If the dataset is a nested detail set, DataSetField indicates what detail dataset to use from the data packet associated with XMLBroker. 

Specify the name of the dataset field as the value of DataSetField. If the dataset is the detail set of a detail set, you can use periods to qualify dataset field names. Thus, for example, if XMLBroker represents a customer dataset with a nested Orders dataset field that has its own nested LineItems field, you can specify the LineItems dataset by setting DataSetField to

Orders.LineItems

XMLBroker 

DataSet 

DataSetPath