Some stores use product ID as an SKU in which case its necessary to display the product ID on the catalog itself. Here’s how do to that:
This is the quick way – ideally this shouldn’t be done on included templates directly but on your own templates in your child theme directory.
Assuming you are using the Vertical Thumbnail List template. Open wp-content/plugins/pdfcatalog2/templates/pdf/thumbnaillist/product.php
<?php echo $post->post_title ?> (should be around line 10 but varies depending on which plugin version is installed). Right before
</h2> on the same line add the following:
(<?php echo $post->ID; ?>)
It should look like this:
<h2 class="product_title"> <a href="<?php echo get_permalink( $post->ID ); ?>"><?php echo $post->post_title ?></a> (<?php echo $post->ID; ?>)</h2>
Save the file, clear the PDF cache and you should now see the product IDs next to each product title.