How do I convert from XPS to PDF/A?

Q: I am using PDFTron to generate PDF/A files from XPS.

The one question I have though is how do I specify that they are PDF/A
I can't seem to find any documentation or examples on this.
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A: You can use 'pdftron.PDF.PDFA.PDFACompliance' class to save
resulting PDFDoc as PDF/A. For example:

PDFNet.Initialize();
PDFNet.SetColorManagement(PDFNet.CMSType.e_lcms);

using (PDFDoc pdfdoc = new PDFDoc()) {
  pdftron.PDF.Convert.FromXps(pdfdoc, xps_filename);
  pdfdoc.Save(filename, 0);
}
PDFACompliance pdf_a = new PDFACompliance(true, filename, null,
PDFACompliance.Conformance.e_Level1B, null, 10, false);
pdf_a.SaveAs(filename + ".pdfa", true);

You may also want to refer to the following sample projects:

Convert: http://www.pdftron.com/pdfnet/samplecode.html#Convert
PDF/A: http://www.pdftron.com/pdfnet/samplecode.html#PDFA