  This document defines the high level metadata necessary to describe the
physical parameter space of observed or simulated astronomical data sets, such
as 2D-images, data cubes, X-ray event lists, IFU data, etc.. The
Characterisation data model is an abstraction which can be used to derive a
structured description of any relevant data and thus to facilitate its
discovery and scientific interpretation. The model aims at facilitating the
manipulation of heterogeneous data in any VO framework or portal. A VO
Characterisation instance can include descriptions of the data axes, the range
of coordinates covered by the data, and details of the data sampling and
resolution on each axis. These descriptions should be in terms of physical
variables, independent of instrumental signatures as far as possible.
  Implementations of this model has been described in the IVOA Note available
at: http://www.ivoa.net/Documents/latest/ImplementationCharacterisation.html
  Utypes derived from this version of the UML model are listed and commented in
the following IVOA Note:
http://www.ivoa.net/Documents/latest/UtypeListCharacterisationDM.html
  An XML schema has been build up from the UML model and is available at:
http://www.ivoa.net/xml/Characterisation/Characterisation-v1.11.xsd
