Tex. Civil Practice and Remedies Code § 140A.057

(a) Any person on whom any civil investigative demand for the production of documentary material has been duly served under this subchapter shall make the material available to the attorney general for inspection and copying during normal business hours on the return date specified in the demand at the person's principal office or place of business or as otherwise may be agreed on by the person and the attorney general. The attorney general shall bear the expense of any copying. The person may substitute copies for originals of all or part of the requested documents if the originals are made available for inspection. The attorney general may elect to obtain or review information in an electronic format. The person shall indicate in writing which, if any, of the documents produced contain trade secrets or confidential information.

(b) The production of documentary material in response to any demand must be made under a sworn certificate in the form the demand designates by a natural person having knowledge of the facts and circumstances relating to the production to the effect that all of the requested material in the possession, custody, or control of the person to whom the demand is directed has been produced.