Create PDF marked content

using GemBox.Pdf;
using GemBox.Pdf.Content.Marked;
using GemBox.Pdf.Objects;

class Program
{
    static void Main()
    {
        // If using the Professional version, put your serial key below.
        ComponentInfo.SetLicense("FREE-LIMITED-KEY");

        using (var document = new PdfDocument())
        {
            var page = document.Pages.Add();

            // Surround the path with the marked content start and marked content end elements.
            var markStart = page.Content.Elements.AddMarkStart(new PdfContentMarkTag(PdfContentMarkTagRole.Span));
            
            var markedProperties = markStart.GetEditableProperties().GetDictionary();

            // Set replacement text for a path, as specified in https://opensource.adobe.com/dc-acrobat-sdk-docs/standards/pdfstandards/pdf/PDF32000_2008.pdf#page=623
            markedProperties[PdfName.Create("ActualText")] = PdfString.Create("H");

            // Add the path that is a visual representation of the letter 'H'.
            var path = page.Content.Elements.AddPath()
                .BeginSubpath(100, 600).LineTo(100, 800)
                .BeginSubpath(100, 700).LineTo(200, 700)
                .BeginSubpath(200, 600).LineTo(200, 800);

            var format = path.Format;
            format.Stroke.IsApplied = true;
            format.Stroke.Width = 10;

            page.Content.Elements.AddMarkEnd();

            document.Save("MarkedContent.pdf");
        }
    }
}