XmlmmCIF equivalent: database_2 Data items in the DATABASE_2 category record details about the database identifiers of the data block. These data items are assigned by database managers and should only appear in a data block if they originate from that source. The somewhat awkward name of this category (DATABASE_2) is a consequence of the name DATABASE having been already used in the CIF core, but used in a manner different from the usage in mmCIF. Since CIF data names, once adopted, cannot be changed, a new category was created. XmlmmCIF equivalent: database_2/database_id An abbreviation that identifies the database. XmlmmCIF equivalent: database_2/database_code The code assigned by the database identified in _database_2.database_id.