- var_dump: documentation ( source)
- explode: documentation ( source)
- array_diff: documentation ( source)
<?php
$flags = array('utf-8,gzip,html,external');
$flags = explode(',', $flags);
$flags = array_diff($flags, ['wikitext']);
var_dump($flags);
$flags = array_diff($flags, ['html']);
var_dump($flags);