(PHP 4 >= 4.0.2, PHP 5, PHP 7) Suggest spellings of a word

(PHP 4 >= 4.3.0, PHP 5, PHP 7) Make a string uppercase

(PHP 4 >= 4.2.0, PHP 5, PHP 7) Split multibyte string using regular expression

(PHP 5 >= 5.3.0, PHP 7, PECL intl >= 1.0.0) Set a text attribute

(PHP 5 >= 5.3.0, PHP 7, PECL intl >= 1.0.0) Set formatter pattern

(PHP 5, PHP 7) Decodes multiple MIME header fields at once

(PHP 7) Check if code point is a whitespace character according to ICU

(PHP >= 5.4.0, PECL intl >= 2.0.0) Get last error message

(PHP 5 >= 5.3.0, PHP 7, PECL intl >= 1.0.0) Searches the language tag list for the best match to the language

(PHP 5.5.0, PHP 7, PECL >= 3.0.0a1) Get the first day of the week for the calendarʼs locale