Piwigo/include/smarty/docs/designers/language-modifiers/language-modifier-lower.md

lower

This is used to lowercase a variable. This is equivalent to the PHP strtolower() function.

<?php

$smarty->assign('articleTitle', 'Two Convicts Evade Noose, Jury Hung.');

?>

Where template is:

{$articleTitle}
{$articleTitle|lower}

This will output:

Two Convicts Evade Noose, Jury Hung.
two convicts evade noose, jury hung.

See also upper and capitalize.