test.cs

// check if there is a SubTextPart at the
// current input position
if (textControl1.SubTextParts.GetItem() == null)
  return;

// retrieve current SubTextPart
SubTextPart stpMergeBlock = textControl1.SubTextParts.GetItem();

// check if SubTextPart is a MergeBlock
if (TXTextControl.DocumentServer.DataSources.DataSourceManager.IsMergeBlock(
  textControl1.SubTextParts.GetItem()) == true) {

  // create a MergeBlockInfo object from SubTextPart
  TXTextControl.DocumentServer.DataSources.MergeBlockInfo mbInfo = 
    new TXTextControl.DocumentServer.DataSources.MergeBlockInfo(stpMergeBlock);

  // add a filter
  mbInfo.Filters.Add(
    new TXTextControl.DocumentServer.DataShaping.FilterInstruction(
      "Price", 
      TXTextControl.DocumentServer.DataShaping.RelationalOperator.GreaterThan,
      500));

  mbInfo.SortingInstructions.Add(
   new TXTextControl.DocumentServer.DataShaping.SortingInstruction(
     "Price",
     TXTextControl.DocumentServer.DataShaping.SortOrder.Ascending));

  // important: apply the settings
  mbInfo.Apply();