// Recursive annotated variations. ("()", OneGame(EmptyTagSection, Plies(Ply(VariationOpenClose))),
// Single move tree symbols. ("0", OneGame(EmptyTagSection, Plies(Ply(MoveNumberNoFloats))), new[] { PgnErrorCode.MissingMove, PgnErrorCode.MissingTagSection, PgnErrorCode.MissingGameTerminationMarker }),