Art. 39.06. WRITTEN INTERROGATORIES.  When any such deposition is to be taken by written interrogatories, such written interrogatories shall be filed with the clerk of the court, and a copy of the same served on all other parties or their counsel for the length of time and in the manner required for service of interrogatories in civil action, and the same procedure shall also be followed with reference to cross-interrogatories as that prescribed in civil actions.
Acts 1965, 59th Leg., vol. 2, p. 317, ch. 722.