Retailers need to be as detailed as possible when listing products on Google Shopping to get the most out of their advertising dollars, according to Rick Backus, CEO and co-founder of comparison shopping site consultancy CPC Strategy.

Backus told attendees at a 2016 Internet Retailer Conference & Exhibition workshop on Friday that a number of his company’s clients had product listings suspended on May 19, what he referred to in his presentation as the “UPoCalypse.” May 19 was the date by which retailers had to attach global trade identification numbers (GTINs) to their goods or risk not showing up on Google Shopping. The most common format for GTINs in North America is the Universal Product Code (UPC).

“If you look at the [Google Shopping] feed, Google is extremely good at organizing data,” he told attendees. Many retailers, however, are not. Retailers would send product listings to Google with information unique to the merchant’s store but which made it difficult for Google to organize, he said.”

With Google’s new GTIN rules in place, Backus recommends retailers list their products on Google Shopping by being as specific as possible, using  three to five levels of product descriptions. He used footwear as an example in a sample product listing. Because Google indexes based on product types, an ideal listing would be  “Apparel > Mens > Dress Shoes > Salvatore Ferragamo > ‘Regal’ Pebbled Leather Loafer,” which details the product, brand and product type.

Backus told attendees that bricks-and-mortar stores should also take advantage of Google’s local inventory ads to show online shoppers what products they have in stores near those shoppers. Doing so could help give retailers with stores an advantage over online-only merchants.

“They’ve opened it up where retailers with three bricks-and-mortar stores can submit local inventory feeds,” he said of Google. “Google wasn’t pushing this [option] a lot on the consumers previously and that’s changing quickly. Local availability is something that allows [retailers] to differentiate the experience. If they have the local availability, they can serve that up with PLAs (Product Listing Ads). If you want to buy online, you can buy through a PLA. If you want to buy it in store, you can see where the nearest store is located and if the product is in stock.”