eBay periodically updates their category tree structures and other data. Ebay generally sends out notifications to customers to let them know of these changes. It's important when these announcements are released that you see if any of your product categories are affected.
If your product categories are affected by changes, you may run into incompatible errors or warnings against listings. Becayse of this, we recommend you regularly update your eBay site data.
If your business is involved in selling car parts, it’s recommended you also tick Also Download Latest eBay Vehicle Compatibility List.