Section 20.4 - Rule 4. Appeal systems definitions and applicability provisions(a)Appeal - (1)In general. An appeal consists of a Notice of Disagreement timely filed to the Board on any issue or issues for which VA provided notice of a decision under 38 U.S.C. 5104 on or after the effective date, as defined in § 19.2(a) of this chapter.(2)Appellant's election for review of a legacy claim or appeal in the modernized review system. The regulations applicable to appeals are also applicable to legacy claims and appeals, as those terms are defined in §§ 3.2400(b) and 19.2(c) of this chapter, where the claimant elects the modernized review system pursuant to § 19.2(d) of this chapter, and upon the timely filing to the Board of a Notice of Disagreement.(b)Applicability of parts 19 and 20 - (1)Appeals. Subparts C, D, E, and I of part 20 apply only to the processing and adjudication of appeals in the modernized review system.(2)Legacy claims and appeals. Part 19 and subparts F, G, and J of part 20 apply only to the processing and adjudication of legacy claims and appeals.(3)Both appeals systems. 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 claims and appeals. Authority: Sec. 2 , Pub. L. 115-55 ; 131 Stat. 1105