nextcloud-server/apps/files_encryption/templates/settings.php

<form id="encryption">
	<fieldset class="personalblock">
		
		<p>
			<strong><?php echo $l->t( 'Encryption' ); ?></strong>
			
			<?php echo $l->t( "Exclude the following file types from encryption:" ); ?>
			<br />
			
			<select 
			id='encryption_blacklist' 
			title="<?php echo $l->t( 'None' )?>" 
			multiple="multiple">
			<?php foreach($_["blacklist"] as $type): ?>
				<option selected="selected" value="<?php echo $type; ?>"> <?php echo $type; ?> </option>
			<?php endforeach;?>
			</select>
		</p>
	</fieldset>
</form>