
    Argued August 18,
    affirmed August 29, 1977
    STATE OF OREGON, Respondent, v. VERNON JOHN JACKSON, Appellant.
    
    (No. 143878, CA 7699)
    568 P2d 697
    J. Michael Alexander, Salem, argued the cause for appellant. With him on the brief was Brown, Burt & Swanson, P.C., Salem.
    James C. Rhodes, Assistant Attorney General, Salem, argued the cause for respondent. With him on the brief were James A. Redden, Attorney General, and W. Michael Gillette, Solicitor General, Salem.
    Before Schwab, Chief Judge, and Richardson and Johnson, Judges.
    PER CURIAM.
   PER CURIAM.

Defendant appeals from a conviction of criminal mischief in the second degree. ORS 164.354. He contends that the trial court erred in failing to require a witness whom he had subpoened to appear. The trial judge refused to do so on the grounds that the witness, a physician, had informally communicated to the judge that he knew nothing about the matter.

We affirm without reaching the question of whether the trial judge’s reasoning was correct, because it is clear that if the doctor had been present the defendant would have sought to elicit from the doctor only impeaching evidence on a collateral matter— which is impermissible.

Affirmed.  