pdf file - The CIDOC CRM

form without loss of meaning. Note that the back-transformation into a CRM-compatible form may
result in a data record that is semantically equivalent but not identical with the original.
Any CRM-compatible form is automatically import-compatible with the CRM. Note that an importcompatible
data structure may be semantically richer than the CRM. It may contain elements that,
through the use of a transformation algorithm, can be made to correspond to CRM concepts or
specializations thereof or that contain elements with meanings that fall outside the scope of the CRM.
However, it must not contain elements that overlap in meaning with CRM concepts and which cannot
be subsumed via transformation by a CRM concept other than E1 CRM Entity and E77 Persistent Item.
Import-compatible data structures may be used to transport data for applications that require concepts
that lie beyond the scope of the CRM, as well as data from any export-compatible data structure. Note
that, in general, applications may make use of data from a CRM import-compatible data structure that
has been exported into a CRM compatible form by semantic reduction to CRM concepts, i.e. by
generalizing all subsumed concepts to the most specific CRM concept applicable, and by discarding
elements that fall outside the scope of the CRM.
A data structure is partially import-compatible with the CRM if the above holds for a reduced CRMcompatible
form.
CRM Compatibility of Information Systems
An information system is export-compatible with the CRM if it is possible to export all user data
from this information system into an import-compatible data structure. This capability is the
recommended kind of CRM-compatibility for local information systems.
An information system is partially export compatible if it is possible to export all user data from this
information system into a partially import-compatible data structure. This is not the recommended kind
of CRM-compatibility, but it may not be feasible for legacy systems to acquire a higher level of CRM
compatibility without unreasonable effort. This reduced level of CRM compatibility is nonetheless
highly useful.
Note that there is no minimum requirement for the classes and properties that must be present in the
exported user data. Therefore it is possible that the data may pertain to instances of just a single
property, such as E21 Person. P131 is identified by: E82 Actor Appellation.
An information system is import-compatible with the CRM if it is possible to import data encoded in
a CRM-compatible form and to access the data in a manner equivalent to and homogeneous with all
generic data of this system that fall under the same concepts. This capability is considered as the normal
kind of CRM compatibility for integrated access systems that physically copy source data in a data
warehouse style (materialized access systems).
An information system is partially import-compatible with the CRM if it is possible to import data
encoded in a reduced CRM-compatible form and to access the data in a manner equivalent to and
homogeneous with all generic data of this system that fall under the same concepts. Depending on the
functional requirements, it makes sense for integrated access systems to offer access services of reduced
complexity by being only partially import-compatible with the CRM.
Note that it makes sense for integrated access systems to import data from extended data structures by
semantic reduction to CRM defined concepts.
Note that local information system providers may choose to make their systems import-compatible with
the CRM in order to exchange data, for example in the case of museum object loans or for system
migration purposes. Communities of practice may choose to agree on import compatibility for extended
data structures.
Some local information systems are likely to focus on specialized subject areas, such as inscriptions.
For these specialized systems, the ability to import a specific data structure is recommended. This
should be export-compatible with the CRM, and encompass the concepts that are required by the subject
Definition of the CIDOC Conceptual Reference Model
vi