<database> A kind of database management system that links records
together like a family tree such that each record type has only one owner, e.g.
an order is owned by only one customer. Hierarchical structures were widely used
in the first mainframe database management systems. However, due to their
restrictions, they often cannot be used to relate structures that exist in the
HIBOL « HID « hidden flag « hierarchical database
» Hierarchical Data Format » hierarchical file
system » Hierarchical Music Specification Language