The petition for writ of prohibition is denied. Motion for rehearing, if any, must be filed by noon, Friday, August 21, 1981.

concurring specially.

I concur with the court’s determination because, in my view, the petitioner has failed to demonstrate that the trial judge is a “material witness,” i. e., that he possesses relevant information “going to some fact affecting the merits of the cause . . . about which no other witness might testify.” Wingate v. Mach, 117 Fla. 104, 157 So. 421, 422 (1934) (emphasis supplied). Rule 8.220(b)(1)(viii), Fla.R.Crim.P., provides a mechanism by which the state may obtain a handwriting exemplar from the defendant. Thus, through the use of expert testimony, there exists an alternate but well-recognized method for establishing the authorship and integrity of the document in question without requiring testimony from the trial judge.