data hierarchy
The system of data objects which provide the methods for
information storage and retrieval. Broadly, a data
hierarchy may be considered to be either natural, which arises
from the alphabet or syntax of the language in which the
information is expressed, or machine, which reflects the
facilities of the computer, both hardware and software.
A natural data hierarchy might consist of bits,
characters, words, phrases, sentences, paragraphs, and
chapters. One might use components bound to an application,
such as field, record, and file, and these would ordinarily be
further specified by having data descriptors such as name
field, address field, etc. On the other hand, a machine or
software system might use bit, byte, word, block,
partition, channel, and port.
Programming languages often provide types or objects which
can create data hierarchies of arbitrary complexity, thus
allowing software system designers to model language
structures described by the linguist to greater or lesser
degree.
The distinction between the natural form of data and the
facilities provided by the machine may be obscure, because
users force their needs into the molds provided, and
programmers change machine designs. As an example, the
natural data type "character" and the machine type "byte" are
often used interchangeably, because the latter has evolved to
meet the need of representing the former.
(1995-11-03)
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