test.cs

public IActionResult Index() {
	
  byte[] data;

  Claim claim = new Claim() {
    name = "Tim Typer",
    dob = new DateTime(2010, 5, 5),
  };

  using (TXTextControl.ServerTextControl tx = new TXTextControl.ServerTextControl()) {
    tx.Create();
    tx.Load("App_Data/claim_form.tx", TXTextControl.StreamType.InternalUnicodeFormat);

    using (MailMerge mailMerge = new MailMerge()) {
      mailMerge.TextComponent = tx;
      mailMerge.FormFieldMergeType = FormFieldMergeType.Preselect;
      mailMerge.MergeObject(claim);
    }

    tx.Save(out data, TXTextControl.BinaryStreamType.InternalUnicodeFormat);
  }

  return View(data);
}