XmlmmCIF equivalent: entity_keywords Data items in the ENTITY_KEYWORDS category specify keywords relevant to the molecular entities. Note that this list of keywords is separate from the list that is used for the STRUCT_BIOL data items, and is intended to provide only the information that one would know about the molecular entity *if one did not know its structure*. Hence polypeptides are simply polypeptides, and not cytokines or beta-alpha-barrels, and polyribonucleic acids are simply poly-RNA, and not transfer- RNA. XmlmmCIF equivalent: entity_keywords/text. Keywords describing this entity. XmlmmCIF equivalent: entity_keywords/pdbx_ec. Enzyme Commission (EC) number(s) XmlmmCIF equivalent: entity_keywords/pdbx_fragment. Entity fragment description(s). XmlmmCIF equivalent: entity_keywords/pdbx_mutation. Entity mutation description(s). XmlmmCIF equivalent: entity_keywords/entity_id. This data item is a pointer to _entity.id in the ENTITY category.