In Shepard v. United States, 533 A.2d 1278, 1280 (D.C. 1987), the Court established that appellants who are "aware of a basis for alleging ineffective assistance of trial counsel" should file 23-110 motions alleging such ineffectiveness during the pendency of the direct appeal as a way of "making a record regarding matters relevant to the ineffectiveness claim that do not appear in the record of the case on direct appeal." 533 A.2d at 1280. To provide some "teeth" to that requirement, we also announced the prospective application of a new rule that if an appellant does not do so, "that procedural default will be a barrier to this court's consideration of appellant's claim." 533 A.2d at 1280 .