Part 19 and subparts F, G, and J of part 20 apply only to the processing and adjudication of legacy appeals, as defined in § 19.2. Except as otherwise provided in specific sections, subparts A, B, H, K, L, M, N, and O of part 20 apply to the processing and adjudication of both appeals and legacy appeals. For applicability provisions concerning appeals in the modernized review system, see § 20.4 of this chapter.