In addition to the id2entry and attribute indexes, LDBM maintains a number of other indexes, including the dn2id index and the id2children index. These indexes provide the mapping between a DN and the corresponding EID, and the mapping between an EID and the EIDs of the corresponding entry's children, respectively.
The dn2id index stores normalized DNs as keys. The data stored is the corresponding EID.
The id2children index stores EIDs as keys. The data stored is a list of EIDs, just as for the attribute indexes.