Macromolecular dictionary (mmCIF) version 2.0.09
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 name of this category, DATABASE_2, arose because the category name DATABASE was already in use in the core CIF dictionary, but was used differently from the way it needed to be used in the mmCIF dictionary. Since CIF data names cannot be changed once they have been adopted, a new category had to be created.Example:
Example 1 - based on PDB entry 5HVP and laboratory records for the
structure corresponding to PDB entry 5HVP.
_database_2.database_id 'PDB' _database_2.database_code '5HVP'
Mandatory category: no