Try to make an array like this:

$vmf = array();
$vmf["world"] = array();
$vmd["world"][0] = array();
$vmd["world"][0]["id"] = 1;
$vmd["world"][0]["skyname"] = "sky_wasteland02";
...
$vmd["world"][0]["solid"] = array();
$vmd["world"][0]["solid"][0] = array();
$vmd["world"][0]["solid"][0]["id"] = 2;
$vmd["world"][0]["solid"][0]["side"] = array();
$vmd["world"][0]["solid"][0]["side"]["id"] = 1;
$vmd["world"][0]["solid"][0]["side"]["plane"] = "(-10791.0 9054.12 2676.0) (-10791.0 9054.12 2664.0) (-10791.0 9897.88 2664.0)";
...
$vmd["world"][0]["solid"][1] = array();
$vmd["world"][0]["solid"][1]["id"] = 2;
$vmd["world"][0]["solid"][1]["side"] = array();
$vmd["world"][0]["solid"][1]["side"]["id"] = 1;
$vmd["world"][0]["solid"][1]["side"]["plane"] = "(-10791.0 9054.12 2676.0) (-10791.0 9054.12 2664.0) (-10791.0 9897.88 2664.0)";
...

";
			} else {
				$keys = array_keys($element);
				$key = $keys[0];
				
				echo $key . "->" . $element[$key];
			}
			
			echo "\n";
		}
?>