Iterating the return value gives you a a string with the time zone ID (ie "Europe/London" or "Etc/GMT-1")
For the constants to use for the `zoneType` argument, see:
https://github.com/php/php-src/blob/master/ext/intl/timezone/timezone_class.cpp#L419-L421
<?php
IntlTimeZone::TYPE_ANY // the whole lot, including aliases like "CST"
IntlTimeZone::TYPE_CANONICAL // the canonical IDs (no aliases)
IntlTimeZone::TYPE_CANONICAL_LOCATION // only IDs for locations (no "Etc/GMT-1")
?>