-<?php echo "<?"; ?>xml version="1.0" encoding="utf-8" <?php echo "?>"; ?>
+<?php echo '<?xml version="1.0" encoding="utf-8"?>'; ?>
<categories>
<?php foreach ($categories as $k){ ?> <category description="<?php echo $k->description; ?>" unit="<?php echo $k->unit; ?>"><?php echo $k->slug; ?></category>