In Brown v. State, 508 S.W.2d 366, 368 (Tex. Crim. App. 1974) the court of criminal appeals held that the trial court abused its discretion by revoking Brown's probation on the basis of his failure to comply with the condition of probation that he "report to the probation officer as directed" because "such requirement standing alone constitutes an improper delegation of the setting of terms of probation to the probation officer." The court observed, however, "The exercise of improperly delegated authority by a probation officer cannot make the delegation effective, although on different facts, where parties over a period of time have accepted such a delegation of authority as shown by the course of conduct between them, a probationer may be estopped from objecting to being held to the duty assumed." Brown, 508 S.W.2d at 368.