Texas Appellate Rule 52.3(k)(1)(A) requires that an appendix to a Petition for Writ of Mandamus must contain a certified or sworn copy of any order complained of, or any other document showing the matter complained of. Appellate courts are very strict in enforcing this requirement. So much so that even when the Respondent trial judge does not dispute how she ruled, the court of appeals will not accept the petition for writ of mandamus unless the order is in the appendix.
Thus, the Dallas Court of Appeals denied a petition for writ of mandamus in In re Oncor Electric Delivery Co., where the relator had not produced a copy of the order complained of–specifically, the trial court’s denial of Oncor’s motion to join responsible third party. Instead, Oncor pointed the court to the transcript of the hearing on Oncor’s motion for rehearing of that issue wherein the trial judge recited at the outset of the hearing, "My understanding is, is that this is Defendant’s motion to reconsider the court’s denial of the responsible third-party motion." The appellate court denied the petition for writ of mandamus due to the failure to provide a definite oral or written ruling of the denial of the motion to join responsible third party. The court’s opinion may be found here.