Several functions were given new, optional parameters in PHP 5.4:
Added the optional
limit parameter to debug_backtrace()
and debug_print_backtrace(), to limit the amount of stack frames returned.
is_link() now works properly for symbolic links on Windows Vista
or later. Earlier systems do not support symbolic links.
idn_to_ascii() and idn_to_utf8() now take two extra
parameters, one indicating the variant (IDNA 2003 or UTS #46) and another, passed by reference,
to return details about the operation in case UTS #46 is chosen.