ISO/Guide 31:2015 is intended to help reference material (RM) producers in preparing clear and concise documentation to accompany an RM. It lists and explains mandatory, recommended and other categories of information to be considered in the preparation of product information sheets and RM certificates. This information can be used by RM users and other stakeholders in confirming the suitability of an RM or certified reference material (CRM). ISO/Guide 31:2015 also contains the minimum requirements for a label attached to the RM container.