The document discusses a study on the persistence of persistent identifiers (PIDs) like DOIs on the scholarly web. The study examined how scholarly publishers responded to common HTTP requests against DOIs using different clients and network environments. It found that responses were often inconsistent, with less than 50% of requests receiving successful responses. Responses varied based on the request method, client, whether the content was open access, and whether the network had a subscription. The inconsistencies could undermine trust in PIDs and persistence was higher for subscribed/licensed content and open access articles.