The ISO 9000 family covers quality management broadly, but only one standard within that family can actually be certified against by an organisation, and that is ISO 9001, which lays out the specific requirements a quality management system must meet. ISO 9000 itself just gives definitions and vocabulary, and ISO 9004 offers guidance for performance improvement rather than a certifiable standard. Because ISO 9001 is the one food companies actually get certified to for quality management, it is the standard being referred to here.