code: public function GIFAddHeader()
      {
  
          if (ord($this->BUF[0]{10}) & 0x80) {
              $cmap = 3 * (2 << (ord($this->BUF[0]{10}) & 0x07));
  
              $this->GIF .= substr($this->BUF[0], 6, 7);
              $this->GIF .= substr($this->BUF[0], 13, $cmap);
              $this->GIF .= "!\377\13NETSCAPE2.0\3\1" . self::GIFWord($this->LOP) . "\0";
          }
      }
docs: /*
  :::::::::::::::::::::::::::::::::::::::::::::::::::
  ::
  ::    GIFAddHeader...
  ::