In Donovan v. Gober, 10 Vet. App. 404, 407-08 (1997), aff'd sub nom., Donovan v. West, 158 F.3d 1377 (Fed. Cir. 1998), cert. denied, U.S. 119 S.Ct. 1255 (1999), the regional office ("RO") denied the veteran's claim for gastric neurosis and psychoneurosis in 1947 and the veteran did not appeal this decision to the Board. In 1985, Mr. Donovan filed another claim for benefits, this time for Post Traumatic Stress Disorder. The RO denied his claim and he appealed to the Board, which denied the request in 1988 and noted that it had reviewed the entire evidence of record and was making a de novo determination of entitlement. In 1991, Mr. Donovan filed a claim for CUE with respect to the 1947 RO decision. Two new VA psychiatric examinations concluded that he had a stress disorder. Given this new and material evidence, the RO granted service connection for the stress disorder with payments effective as of 1991. Mr. Donovan requested that payments be made retroactive to 1947. The RO denied this request and Mr. Donovan appealed to the Board, which affirmed by holding that his claim that the 1947 RO decision contained CUE was without legal merit because the 1947 RO decision had been subsumed by the 1988 Board decision, which had reviewed the record de novo. The 1947 RO decision was therefore "immune from collateral attack under a theory of CUE." Donovan, 158 F.3d at 1380. The Court of Appeals for Veterans Claims affirmed this application of the doctrine of delayed-subsuming. The court also affirmed, holding that the 1988 Board decision implicitly made a determination that the 1947 decision did not include clear and unmistakable error ("CUE"). The Court held that the 1988 Board decision not only focused on whether the claim should be reopened but also determined the merits of the underlying question of service connection. The Court found the 1988 Board made a de novo review and essentially reviewed the 1947 decision as if the Board were acting in a direct appeal. The 1988 Board decision therefore "subsumed" the 1947 RO decision, rendering the initial RO denial immune from collateral attack. The Court explained that the 1988 Board decision had to bar Mr. Donovan's CUE claim because (1) it would place the RO in the improper position of reviewing an appellate tribunal and (2) the Board decision was final and could not be reopened on the same factual basis. See 38 U.S.C. 7104(a), (b). Therefore, Donovan was our first case to hold that there could be a subsuming of an unappealed, final RO decision by a later Board decision even if the claim of CUE had not been raised or argued by the appellant to the Board--a "delayed-subsuming."