(PHP 5 >= 5.5.0, PHP 7, PECL >= 3.0.0a1)
IntlCalendar::getKeywordValuesForLocale — Get set of locale keyword values
Object oriented style
$key
   , string $locale
   , bool $commonlyUsed
   ) : IteratorProcedural style
$key
   , string $locale
   , bool $commonlyUsed
   ) : Iterator
   For a given locale key, get the set of values for that key that would result
   in a different behavior. For now, only the 'calendar'
   keyword is supported.
  
This function requires ICU 4.2 or later.
key
      The locale keyword for which relevant values are to be queried. Only
      'calendar' is supported.
     
localeThe locale onto which the keyword/value pair are to be appended.
commonlyUsedWhether to show only the values commonly used for the specified locale.
   An iterator that yields strings with the locale keyword
   values or FALSE on failure.
  
Example #1 IntlCalendar::getKeyworkValuesForLocale()
<?php
print_r(
        iterator_to_array(
                IntlCalendar::getKeywordValuesForLocale(
                        'calendar', 'fa_IR', true)));
print_r(
        iterator_to_array(
                IntlCalendar::getKeywordValuesForLocale(
                        'calendar', 'fa_IR', false)));
The above example will output:
Array
(
    [0] => persian
    [1] => gregorian
    [2] => islamic
    [3] => islamic-civil
)
Array
(
    [0] => persian
    [1] => gregorian
    [2] => islamic
    [3] => islamic-civil
    [4] => japanese
    [5] => buddhist
    [6] => roc
    [7] => hebrew
    [8] => chinese
    [9] => indian
    [10] => coptic
    [11] => ethiopic
    [12] => ethiopic-amete-alem
)