Abstract

HDS is a file-based hierarchical data system designed for the storage of a wide variety of information. It is particularly suited to the storage of large multi-dimensional arrays (with their ancillary data) where efficient access is needed.

HDS organises data into hierarchies, broadly similar to the directory structure of a hierarchical filing system, but contained within a single HDS container file. The structures stored in these files are self-describing and flexible; HDS supports modification and extension of structures previously created, as well as deletion, copying, renaming, etc.

All information stored in HDS files is portable between the machines on which HDS is implemented. Thus, there are no format conversion problems when moving between machines.

The routines described in this document may be used to perform operations on any HDS data. In addition, HDS forms a toolkit for the construction of higher level (more specialised) data structures and the software which accesses them. HDS routines are therefore invoked indirectly by many other items of Starlink software.