References and unsetting vars pointed by them

If I have this code

$s = 22;
$r = &$s;

// do something


Does $r stay into memory until it falls out of scope? For that matter, any other references that pointed to $s?

PHP references as “symbol table aliases”, more akin to hard-linking a UNIX file than a C pointer.

In this case, $s becomes unset and $r (and any other references to $s) retains the previous value (22).