WordNet (r) 3.0 (2006):

data hierarchy
    n 1: an arrangement of data consisting of sets and subsets such
         that every subset of a set is of lower rank than the set

The Free On-line Dictionary of Computing (30 December 2018):

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)