date_default_timezone_set() sets the default timezone
used by all date/time functions.
Замечание:
Since PHP 5.1.0 (when the date/time functions were rewritten), every call
to a date/time function will generate a E_NOTICE if
the timezone isn't valid, and/or a E_STRICT message
if using the system settings or the TZ environment
variable.
Список параметров
timezone_identifier
The timezone identifier, like UTC or
Europe/Lisbon. The list of valid identifiers is
available in the Прил. H.
Возвращаемые значения
This function always returns TRUE (even if the
timezone_identifier isn't valid).