However, many problems remain because originators often fail to produce online reports or publications to an adequate bibliographic standard (often omitting a publication date, for instance). Documents are often not assigned permanent URLs or DOI numbers, or stored in electronic depositories, so that link rot can develop within citations, reference lists, databases and websites. Copyright law and the copyrighted status of many reports inhibits their downloading and electronic storage and there is a lack of large scale collecting of digital grey literature. Securing long-term access to and management of grey literature in the digital era thus remains a considerable problem.