inline Standard_ExtCharacter ConvertToUnicode3B (unsigned char *p)
 {
   // *p, *(p+1), *(p+2) =>0 , 1, 2
+  // little endian
   union {
     struct {
-      unsigned char  h;
       unsigned char  l;
+      unsigned char  h;
     } hl;

Utf16 SOURCE:
57 00 3A 00 5C 00 50 00|61 00 72 00 74 00 31 00
5F 00 62 00 61 00 64 00|6E 00 61 00 6D 00 65 00
5F 00 DE 30 F9 30 F1 30|2E 00 69 00 67 00 73 00

Utf16 TCol from Utf8:
57 00 3A 00 5C 00 50 00|61 00 72 00 74 00 31 00
5F 00 62 00 61 00 64 00|6E 00 61 00 6D 00 65 00
5F 00 DE 30 F9 30 F1 30|2E 00 69 00 67 00 73 00

Utf16 NCol from Utf8:
57 00 3A 00 5C 00 50 00|61 00 72 00 74 00 31 00
5F 00 62 00 61 00 64 00|6E 00 61 00 6D 00 65 00
5F 00 DE 30 F9 30 F1 30|2E 00 69 00 67 00 73 00

Utf8  WApi from Utf16:
57 3A 5C 50 61 72 74 31|5F 62 61 64 6E 61 6D 65
5F E3 83 9E E3 83 B9 E3|83 B1 2E 69 67 73
Utf8  NCol from Utf16:
57 3A 5C 50 61 72 74 31|5F 62 61 64 6E 61 6D 65
5F E3 83 9E E3 83 B9 E3|83 B1 2E 69 67 73
Utf8  TCol from Utf16:
57 3A 5C 50 61 72 74 31|5F 62 61 64 6E 61 6D 65
5F E3 83 9E E3 83 B9 E3|83 B1 2E 69 67 73

static TCollection_AsciiString formatHex (const Standard_Byte* theData,
                                          const Standard_Size  theSize)
{
  TCollection_AsciiString anOut;
  char aByte[4];
  for (size_t aByteId = 0; aByteId < theSize; ++aByteId)
  {
    unsigned char aChar = theData[aByteId];
    char anEsc = ' ';
    if (     (aByteId + 1) % 16 == 0 && aByteId != 0)
    {
      anEsc = '\n';
    }
    else if ((aByteId + 1) % 8  == 0)
    {
      anEsc = '|';
    }
    _snprintf (aByte, 4, "%02X%c", (unsigned int )aChar, anEsc);
    anOut += aByte;
  }
  return anOut;
}

static Standard_Integer testunicode (Draw_Interpretor& /*theDI*/, Standard_Integer , const char** )
{
  wchar_t aFilePath [MAX_PATH]; aFilePath [0] = L'\0';
  wchar_t aFileTitle[MAX_PATH]; aFileTitle[0] = L'\0';
  OPENFILENAMEW anOpenStruct; memset (&anOpenStruct, 0, sizeof(OPENFILENAMEW));
  anOpenStruct.lStructSize     = sizeof(OPENFILENAMEW);
  anOpenStruct.nFilterIndex    = 1;
  anOpenStruct.lpstrFile       = aFilePath;
  anOpenStruct.nMaxFile        = sizeof(aFilePath);
  anOpenStruct.lpstrFileTitle  = aFileTitle;
  anOpenStruct.nMaxFileTitle   = sizeof(aFileTitle);
  anOpenStruct.lpstrTitle      = L"No Title";
  anOpenStruct.Flags = OFN_PATHMUSTEXIST | OFN_FILEMUSTEXIST;
  if (!GetOpenFileNameW (&anOpenStruct)
   || *anOpenStruct.lpstrFile == L'\0')
  {
    return 0;
  }

  char aBuffU8[4096];
  WideCharToMultiByte (CP_UTF8, 0, anOpenStruct.lpstrFile, -1, aBuffU8, 4096, NULL, NULL);
  NCollection_String anUtf8NCol (anOpenStruct.lpstrFile, -1);

  char aBuffU8UsingExt[4096];
  char* aPtr = aBuffU8UsingExt;
  TCollection_ExtendedString anExtWide ((Standard_ExtString )anOpenStruct.lpstrFile);
  anExtWide.ToUTF8CString (aPtr);

  TCollection_AsciiString aHexUtf16Src = formatHex ((const Standard_Byte* )anOpenStruct.lpstrFile, wcslen (anOpenStruct.lpstrFile) * 2);
  TCollection_AsciiString aHexUtf8WApi = formatHex ((const Standard_Byte* )aBuffU8, strlen(aBuffU8));
  TCollection_AsciiString aHexUtf8NCol = formatHex ((const Standard_Byte* )anUtf8NCol.ToCString(), anUtf8NCol.Size());
  TCollection_ExtendedString anExtWideFromUtf8 (aBuffU8, Standard_True);
  TCollection_AsciiString aHexUtf16ExtFromU8 = formatHex ((const Standard_Byte* )anExtWideFromUtf8.ToExtString(), anExtWideFromUtf8.Length() * 2);

  TCollection_AsciiString aHexUtf8TColEx = formatHex ((const Standard_Byte* )aBuffU8UsingExt, strlen(aBuffU8UsingExt));

  NCollection_UtfWideString anUtf16NColFromUtf8 (aBuffU8, -1);
  TCollection_AsciiString aHexUtf16NColFromU8 = formatHex ((const Standard_Byte* )anUtf16NColFromUtf8.ToCString(), anUtf16NColFromUtf8.Size());

  std::cerr << "Utf16 SOURCE:\n"         << aHexUtf16Src << "\n"
            << "Utf16 TCol from Utf8:\n" << aHexUtf16ExtFromU8  << "\n"
            << "Utf16 NCol from Utf8:\n" << aHexUtf16NColFromU8 << "\n"
            << "Utf8  WApi from Utf16:\n" << aHexUtf8WApi  << "\n"
            << "Utf8  NCol from Utf16:\n" << aHexUtf8NCol  << "\n"
            << "Utf8  TCol from Utf16:\n" << aHexUtf8TColEx  << "\n";
  return 0;
}