protected function _blockHeader($xbeg, $xlen, $ybeg, $ylen)
{
if ($xlen != 1) {
$xbeg .= ',' . $xlen;
}
if ($ylen != 1) {
$ybeg .= ',' . $ylen;
}
return "@@ -{$xbeg} +{$ybeg} @@";
}