Set oFSO = CreateObject("Scripting.FileSystemObject")
    Set oTXT = oFSO.OpenTextFile(FileName1, ForReading)
    Debug.Print "ansi", oTXT.ReadLine
    oTXT.Close

    Set oFSO = CreateObject("Scripting.FileSystemObject")
    Set oTXT = oFSO.OpenTextFile(FileName2, ForReading, , TristateTrue)
    Debug.Print "unicode", oTXT.ReadLine
    oTXT.Close

Function IsUnicodeTXT(ByVal sFileName As String) As Boolean
    Dim k As Integer
    Dim buf(0 To 3) As Byte
    Dim lLOF As Long
    
    k = FreeFile
    Open sFileName For Binary Access Read As #k
    lLOF = LOF(k)
    Get #k, , buf()
    Close #k
    
    Select Case True
        Case lLOF >= 4 And Hex(buf(0)) = "FF" And Hex(buf(1)) = "FE" And Hex(buf(2)) = "0" And Hex(buf(3)) = "0"
            IsUnicodeTXT = True ' UTF-32LE
        Case lLOF >= 4 And Hex(buf(0)) = "0" And Hex(buf(1)) = "0" And Hex(buf(2)) = "FE" And Hex(buf(3)) = "FF"
            IsUnicodeTXT = True ' UTF-32BE
        Case lLOF >= 3 And Hex(buf(0)) = "EF" And Hex(buf(1)) = "BB" And Hex(buf(2)) = "BF"
            IsUnicodeTXT = True ' UTF-32LE
        Case lLOF >= 2 And Hex(buf(0)) = "FF" And Hex(buf(1)) = "FE"
            IsUnicodeTXT = True ' UTF-16LE
        Case lLOF >= 2 And Hex(buf(0)) = "FE" And Hex(buf(1)) = "FF"
            IsUnicodeTXT = True ' UTF-16BE
    End Select
End Function

Private Declare Function IsTextUnicode Lib "advapi32" (ByVal lpBuffer As String, ByVal cb As Long, lpi As Long) As Long

Private Const IS_TEXT_UNICODE_ASCII16 = &H1
Private Const IS_TEXT_UNICODE_CONTROLS = &H4
Private Const IS_TEXT_UNICODE_DBCS_LEADBYTE = &H400
Private Const IS_TEXT_UNICODE_ILLEGAL_CHARS = &H100
Private Const IS_TEXT_UNICODE_NOT_ASCII_MASK = &HF000
Private Const IS_TEXT_UNICODE_NOT_UNICODE_MASK = &HF00
Private Const IS_TEXT_UNICODE_NULL_BYTES = &H1000
Private Const IS_TEXT_UNICODE_ODD_LENGTH = &H200
Private Const IS_TEXT_UNICODE_REVERSE_ASCII16 = &H10
Private Const IS_TEXT_UNICODE_REVERSE_CONTROLS = &H40
Private Const IS_TEXT_UNICODE_REVERSE_MASK = &HF0
Private Const IS_TEXT_UNICODE_REVERSE_SIGNATURE = &H80
Private Const IS_TEXT_UNICODE_REVERSE_STATISTICS = &H20
Private Const IS_TEXT_UNICODE_SIGNATURE = &H8
Private Const IS_TEXT_UNICODE_STATISTICS = &H2
Private Const IS_TEXT_UNICODE_UNICODE_MASK = &HF

Private Declare Function IsTextUnicode Lib "advapi32" (ByVal lpBuffer As String, ByVal cb As Long, lpi As Long) As Long
Private Declare Function IsTextPointerUnicode Lib "advapi32" Alias "IsTextUnicode" (ByVal lpBuffer As Long, ByVal cb As Long, lpi As Long) As Long


Function IsUTF16TXT(ByVal sFileName As String) As Boolean
    Dim k As Integer
    Dim buf() As Byte
    Dim lLOF As Long
    
    k = FreeFile
    Open sFileName For Binary Access Read As #k
    lLOF = LOF(k)
    ReDim buf(lLOF)
    Get #k, , buf()
    Close #k

Debug.Print Hex(buf(0)), Hex(buf(1))

'    IsUTF16TXT = IsTextPointerUnicode(StrPtr(buf), UBound(buf) + 1, IS_TEXT_UNICODE_STATISTICS + IS_TEXT_UNICODE_SIGNATURE + IS_TEXT_UNICODE_REVERSE_SIGNATURE)
    IsUTF16TXT = IsTextPointerUnicode(StrPtr(buf), UBound(buf) + 1, IS_TEXT_UNICODE_UNICODE_MASK)
End Function