On page http://www.garykessler.net/library/file_sigs.html is listed some various signatures for Powerpoint signature (before Microsoft Office 2007).

I double checked the conversion to ASCII multiple times. The recognition of a Microsoft Office document on the first line is seen. However, I cannot get a recognition of the second level to detect which type it is.

I have this:

            ' If this is a Microsoft Office file
            If Left(lcString, 8) = Chr(208) + Chr(207) + Chr(17) + Chr(224) + Chr(161) + Chr(177) + Chr(26) + Chr(225) Then

                ' If this is a Word file
                If Mid(lcString, 513, 4) = Chr(236) + Chr(165) + Chr(193) + Chr(0) Then
                    cExtension = "DOC"
                    nNoFileType = 1
                    Return True
                End If

                ' If this is a Excel file
                If Mid(lcString, 513, 8) = Chr(9) + Chr(8) + Chr(16) + Chr(0) + Chr(0) + Chr(6) + Chr(5) + Chr(0) Then
                    cExtension = "XLS"
                    nNoFileType = 3
                    Return True
                End If

                ' If this is a Powerpoint file
                If Mid(lcString, 513, 4) = Chr(160) + Chr(70) + Chr(29) + Chr(240) Or _
                 Mid(lcString, 513, 8) = Chr(253) + Chr(255) + Chr(255) + Chr(255) + Chr(14) + Chr(0) + Chr(0) + Chr(0) Or _
                 Mid(lcString, 513, 8) = Chr(253) + Chr(255) + Chr(255) + Chr(255) + Chr(28) + Chr(0) + Chr(0) + Chr(0) Or _
                 Mid(lcString, 513, 8) = Chr(253) + Chr(255) + Chr(255) + Chr(255) + Chr(67) + Chr(0) + Chr(0) + Chr(0) Or _
                 Mid(lcString, 513, 4) = Chr(0) + Chr(110) + Chr(30) + Chr(240) Or _
                 Mid(lcString, 513, 4) = Chr(15) + Chr(0) + Chr(232) + Chr(3) Then
                    cExtension = "PPT"
                    nNoFileType = 5
                    Return True
                End If

                cMessage = cUnableToFindTheOfficeDocumentType
                Return False
            End If

It seems there is another signature that Powerpoint is using. Anyone knows what it is? I have a PPT document here dated from the older versions. This is a binary file. But, it doesn't match any of the above signatures.