''' <summary>
''' Saves PDF document as a PDF/A document.
''' </summary>
Public Shared Sub SaveAsPdfADocument(sourceFilename As String, destFilename As String, ByRef errors As Integer, ByRef warnings As Integer)
    ' load PDF document
    Using document As New Vintasoft.Imaging.Pdf.PdfDocument(sourceFilename)
        errors = 0
        warnings = 0
        ' clear runtime errors and warnings
        document.ClearRuntimeMessages()

        ' save PDF document as PDF/A document
        document.Pack(destFilename, Vintasoft.Imaging.Pdf.PdfFormat.Pdf_A)

        ' check runtime errors and warnings
        For Each message As Vintasoft.Imaging.Pdf.PdfRuntimeMessage In document.RuntimeMessages
            If TypeOf message Is Vintasoft.Imaging.Pdf.PdfRuntimeWarning Then
                warnings += 1
            ElseIf TypeOf message Is Vintasoft.Imaging.Pdf.PdfRuntimeError Then
                errors += 1
            End If
        Next
    End Using
End Sub

/// <summary>
/// Saves PDF document as a PDF/A document.
/// </summary>
public static void SaveAsPdfADocument(
    string sourceFilename, string destFilename, out int errors, out int warnings)
{
    // load PDF document
    using (Vintasoft.Imaging.Pdf.PdfDocument document = 
        new Vintasoft.Imaging.Pdf.PdfDocument(sourceFilename))
    {
        errors = 0;
        warnings = 0;
        // clear runtime errors and warnings
        document.ClearRuntimeMessages();

        // save PDF document as PDF/A document
        document.Pack(destFilename, Vintasoft.Imaging.Pdf.PdfFormat.Pdf_A);

        // check runtime errors and warnings
        foreach (Vintasoft.Imaging.Pdf.PdfRuntimeMessage message in document.RuntimeMessages)
        {
            if (message is Vintasoft.Imaging.Pdf.PdfRuntimeWarning)
                warnings++;
            else if (message is Vintasoft.Imaging.Pdf.PdfRuntimeError)
                errors++;
        }
    }
}