public static void Poc_TestPdfA()
        {
            // Testing with Adobe Preflight, 11.0.20
            // EO.Pdf from NuGet version 18.2.74

            var docA = new PdfDocument();
            docA.Standard = PdfStandard.PDF_A;
            HtmlToPdf.ConvertHtml("Page A text text text text text text", docA);
            docA.Save(@"C:\Temp\EO-docA.pdf");
            // docA Claims to be PDF/A-1a 
            // Adobe Preflight: "Verify compliance with PDF/A-1a": No problems found
            
            var docB = new PdfDocument();
            docB.Standard = PdfStandard.PDF_A;
            HtmlToPdf.ConvertHtml("Page B text text text text text text", docB);
            docB.Save(@"C:\Temp\EO-docB.pdf");
            // docB Claims to be PDF/A-1a 
            // Adobe Preflight: "Verify compliance with PDF/A-1a": No problems found

            var docAB_1 = PdfDocument.Merge(docA, docB);
            docAB_1.Save(@"C:\Temp\EO-docAB_1.pdf");
            // Claims to be PDF/A-1a
            // Adobe Preflight: "Verify compliance with PDF/A-1a": VERIFICATION FAILED
            //      * Transparency used (page is a transparency group)
            //      * CIDset in subset font missing    ( This seems to be regarding the text "Created with EO.Pdf for .NET trial version. http://www.essentialobjects.com.")

            var docAB_2 = PdfDocument.Merge(docA, docB);
            docAB_2.Standard = PdfStandard.PDF_A;
            docAB_2.Save(@"C:\Temp\EO-docAB_2.pdf");
            // Claims to be PDF/A-1a 
            // Adobe Preflight: "Verify compliance with PDF/A-1a": No problems found


            // ** Test Mix of PDF and PDF/A **

            var docC = new PdfDocument();
            docC.Standard = PdfStandard.None;
            HtmlToPdf.ConvertHtml("Page C text text text text text text", docC);
            docC.Save(@"C:\Temp\EO-docC.pdf");
            // docC Claims to be PDF
            

            var docAC_1 = PdfDocument.Merge(docA, docC);
            docAC_1.Save(@"C:\Temp\EO-docAC_1.pdf");
            // docAC_1 Claims to be PDF/A-1a
            // Adobe Preflight: "Verify compliance with PDF/A-1a": VERIFICATION FAILED
            //      * Transparency used (page is a transparency group)
            //      * CIDset in subset font missing    ( This seems to be regarding the text "Created with EO.Pdf for .NET trial version. http://www.essentialobjects.com.")

            var docAC_2 = PdfDocument.Merge(docA, docC);
            docAC_2.Standard = PdfStandard.None;
            docAC_2.Save(@"C:\Temp\EO-docAC_2.pdf");
            // docAC_2 Claims to be PDF/A-1a
            // Adobe Preflight: "Verify compliance with PDF/A-1a": VERIFICATION FAILED
            //      * Transparency used (page is a transparency group)
            //      * CIDset in subset font missing    ( This seems to be regarding the text "Created with EO.Pdf for .NET trial version. http://www.essentialobjects.com.")

            var docAC_3 = PdfDocument.Merge(docA, docC);
            docAC_3.Standard = PdfStandard.PDF_A;
            docAC_3.Save(@"C:\Temp\EO-docAC_3.pdf");
            // docAC_3 Claims to be PDF/A-1a 
            // Adobe Preflight: "Verify compliance with PDF/A-1a": No problems found


            var docCA_1 = PdfDocument.Merge(docC, docA);
            docCA_1.Save(@"C:\Temp\EO-docCA_1.pdf");
            // docCA_1 Claims to be PDF

            var docCA_2 = PdfDocument.Merge(docC, docA);
            docCA_2.Standard = PdfStandard.None;
            docCA_2.Save(@"C:\Temp\EO-docCA_2.pdf");
            // docCA_2 Claims to be PDF

            var docCA_3 = PdfDocument.Merge(docC, docA);
            docCA_3.Standard = PdfStandard.PDF_A;
            docCA_3.Save(@"C:\Temp\EO-docCA_3.pdf");
            // docCA_3 Claims to be PDF
        }

var docAB_1 = PdfDocument.Merge(docA, docB);
docAB_1.Save(@"C:\Temp\EO-docAB_1.pdf");

HtmlToPdf.Options.JpegQualityLevel = 70;
var pdf1 = new PdfDocument();
HtmlToPdf.ConvertUrl("https://www.essentialobjects.com/AboutUs.aspx", pdf1);
pdf1.Standard = PdfStandard.PDF_A;
pdf1.Save(@"C:\temp\EO-AboutUs.pdf");

public static void Poc3()
{
            var pdf3 = new PdfDocument();
            HtmlToPdf.ConvertUrl(url, pdf3);
            var copy = pdf3.Clone();
            copy.Standard = PdfStandard.PDF_A;
            copy.Save(@"C:\temp\EO-AboutUs-Clone.pdf"); 
            // The file will not be a PDF/A. The file is not highlighted as PDF/A when it opens in Adobe Acrobat.
}