1. hierarchical 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 real world. Hierarchical Data Format format, data> HDF A library and multi-object file format for the transfer of graphical and numerical data between computeres. The freely available HDF distribution consists of the library, command line utilities, test suite source, Java interface, and the Java-based HDF Viewer JHV. HDF supports several different data models, including multidimensional arrays, raster images, and tables. Each defines a specific aggregate data type and provides an API for reading, writing, and organising the data and metadata. New data models can be added by the HDF developers or users. HDF is self-describing, allowing an application to interpret the structure and contents of a file without any outside information. One HDF file can hold a mixture of related objects which can be accessed as a group or as individual objects. Users can create their own grouping structures called "vgroups". HDF files can be shared across most common platforms, including many workstations and high performance computers. An HDF file created on one computer can be read on a different system without modification. Home http://hdf. ncsa. uiuc. edu/.
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