    bool isCrwType(BasicIo& iIo, bool advance)
    {
        bool result = true;
        byte tmpBuf[14];
        iIo.read(tmpBuf, 14);
        if (iIo.error() || iIo.eof()) {
            return false;
        }
        if (!(   ('I' == tmpBuf[0] && 'I' == tmpBuf[1])
              || ('M' == tmpBuf[0] && 'M' == tmpBuf[1]))) {
            result = false;
        }
        if (   true == result
            && std::memcmp(tmpBuf + 6, CiffHeader::signature(), 8) != 0) {
            result = false;
        }
        if (!advance || !result) iIo.seek(-14, BasicIo::cur);
        return result;
    }
Unknown