22 Tex. Admin. Code § 367.4
Responsible Master licensees shall display the frameable certificate license in their place of business and all licensees shall carry the pocket card license with them while engaged in work. Each responsible master plumber shall display permanently the master plumber license number and company name on both sides of all service vehicles used in conjunction with plumbing contracting by the responsible master plumber for the purposes of this rule a magnetic sign on a vehicle is not a permanent sign. The letters and numbers shall be not less than two inches high and shall be in a color sufficiently different from the body of the vehicle so that the letters and numbers shall be plainly legible at a distance of not less than 100 feet.
Source Note:The provisions of this §367.4 adopted to be effective August 25, 1993, 18 TexReg 5400; amended to be effective April 15, 1994, 19 TexReg 2280; amended to be effective June 7, 1996, 21 TexReg 4689; amended to be effective October 14, 1996, 21 TexReg 9447.