public string LanguageCode {get; set;}

{
  //Export a single page layout to PDF.

  //Create a PDF format with appropriate settings
  //BMP, EMF, EPS, GIF, JPEG, PNG, SVG, TGA, and TFF formats are also available for export
  string filePath = @"Path and file name for the output export file";
  PDFFormat PDF = new PDFFormat()
  {
    OutputFileName = filePath,
    Resolution = 300,
    DoCompressVectorGraphics = true,
    DoEmbedFonts = true,
    HasGeoRefInfo = true,
    ImageCompression = ImageCompression.Adaptive,
    ImageQuality = ImageQuality.Best,
    LayersAndAttributes = LayersAndAttributes.LayersAndAttributes
  };

  //Check to see if the path is valid and export
  if (PDF.ValidateOutputFilePath())
  {
    //Note: Must be on QueuedTask.Run
    layout.Export(PDF);  //Export the layout to PDF on the worker thread
  }
}

{
  //Export a map series with multiple pages to a single PDF.
  string filePath = @"Path and file name for the output export file";
  //Create PDF format with appropriate settings
  PDFFormat MS_PDF = new PDFFormat()
  {
    OutputFileName = filePath,
    Resolution = 300,
    DoCompressVectorGraphics = true,
    DoEmbedFonts = true,
    HasGeoRefInfo = true,
    ImageCompression = ImageCompression.Adaptive,
    ImageQuality = ImageQuality.Best,
    LayersAndAttributes = LayersAndAttributes.LayersAndAttributes
  };

  //Set up map series export options
  MapSeriesExportOptions MS_ExportOptions = new MapSeriesExportOptions()
  {
    ExportPages = ExportPages.Custom,  //Provide a specific list of pages
    CustomPages = "1-3, 5",  //Only used if ExportPages.Custom is set
    ExportFileOptions = ExportFileOptions.ExportAsSinglePDF,  //Export all pages to a single, multi-page PDF
    ShowSelectedSymbology = false  //Do no show selection symbology in the output
  };

  //Export on the worker thread
  //Note: Must be on QueuedTask.Run
  //Check to see if the path is valid and export
  if (MS_PDF.ValidateOutputFilePath())
  {
    layout.Export(MS_PDF, MS_ExportOptions);  //Export to PDF
  }
}