public override async Task WriteAsync(ISyntaxWriter writer, CancellationToken cancellationToken) { if (writer == null) { throw new ArgumentNullException(nameof(writer)); } await writer.WriteCommentAsync($"PDF-{MajorVersion}.{MinorVersion}", cancellationToken); if (DocumentType == DocumentType.Binary) { await writer.WriteCommentAsync(BinaryMarker, cancellationToken); } }