atasets will be used to fill the in memory dataset, 
    if you select more than one dataset, the numer of fields and field types must 
    be the same.</li>
  <li>Group the union, by selecting union grouping, the in memory dataset will 
    by grouped by the fields specified in the Index Fields property.</li>
  <li>Stablish master detail relationships, this is a filter based on fields of 
    another dataset. Use the <strong>Master Fields property combined with Index 
    Fields</strong> property to perfor