3.1.1 Reference Code
Purpose - To uniquely identify the unit of description and to provide a link to the description that represents it.
Rule – Record as necessary for unique identification, the following elements:
- The country code in accordance with the latest version of ISO 3166 Codes for the representation of names of countries
- The repository code in accordance with the national repository code standard or other unique location identifier
- A specific local reference code, control number, or other unique identifier
All three elements must be present for the purpose of information exchange at the international level.
For information exchange at the international level, it is now necessary to consider the wider discourse around persistent identifiers. See the following for an archivist friendly (but slightly out of date) introduction to this topic - http://www.paradigm.ac.uk/workbook/metadata/pids.html. It is suggested that individual repositories should take and then publish the approach they choose to adopt to address this issue. For example, the Archives Hub explain their approach and reasoning here - http://archiveshub.ac.uk/identifiers/
For born digital archives, it is also likely that identifiers may be automatically generated on ingest, e.g. see the ‘System No.’ as recorded on this catalogue entry for material held at the Wellcome Library;
As can also be seen from this entry, what is perhaps starting to emerge is that there may need to be multiple ‘unique’ identifiers for the same thing. Consequently there may also be a need to distinguish between (and link together in some way) unique identifiers proper (possibly further complicated by the need for internal unique identifiers - possibly system generated - and external – for international information exchange purposes – identifiers in line with one of the persistent identifier schemes commonly in use on the internet more widely) and archival reference codes (which as we know are not just identifiers but also a means of conveying information about the contextual placing of the unit of description in an intellectual hierarchy).
Archival reference codes reflecting traditional ‘arrangement’ will however continue to be necessary, at least for hybrid archives where the decision is taken to include digital material within existing arrangements, but the practice poses difficulties (see further notes under system of arrangement).
As a general principle, archives are encouraged to think more in terms of identification using (potentially) more than one identifier rather than single traditional archival reference codes. Identifiers should not be allowed to multiply excessively though and the aim should always be for the minimum number possible, whilst maintaining clarity of purpose for any identifiers created. Care should be taken to ensure that where identifiers are being asked to convey information beyond simple identity this is properly understood and the implications considered, e.g. if you add in elements to reference codes to indicate whether the item being described is digital or not, or to indicate if the code has been machine generated or not, will that confuse matters later or not?
It should also be remembered that, in the case of born digital material, it is quite possible that there will be multiple versions or manifestations of the ‘same’ thing, e.g. an access copy and a preservation copy, or an ‘original’ version and a number of migrated versions.