can anyone tell me whats going on with this simple bit of code?

[rickrichards82]

i really don't know whats going on with this bit of code. can someone give me detailed information on whats going on? even a few key words to search for so that i can look up some tutorials? at first i thought they were arrays but then when i looked up arrays i realized that this is not the case. anyone?

$this->registry =& $registry;
$this->userinfo = $userinfo;