This recommended practice defines metadata indicators to be used to indicate free-to-read content and a link to license terms for the use/re-use of that content. Humans and machines will be able to assess the status of the content based on these indicators and in many cases the combination of the free_to_read and license_reference metadata will indicate Open Access content. The indicators include a date component so that content with access and re-use rights that change over time can be adequately understood by both humans and machines using the metadata.
In September 2020, a new NISO work item proposal was approved by NISO members to develop metadata and indicators that enable metadata users—including content platforms—to further qualify or scope the license being conveyed. For example, allowing publishers and platforms to utilize ALI tagging to establish sharing policies for a given research article using a specific permissioning framework. To meet this need, an additional attribute definition (applies_to) is added to this Recommended Practice.
See code examples related to Appendix A, Means of Expressing Metadata Elements: http://www.niso.org/schemas/ali/