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MDA Codes

What is an MDA Code?

As part of its work with documentation standards the Collections Trust (and its predecessor body MDA) has, since the 1970s, been developing and maintaining a scheme which allows the identification of UK collection-holding organisations and their collections through “codes” which are unique to each organisation.

An MDA Code is usually made up of five letters – the first three being an abbreviation of the town or village where the organisation is located, followed by two letters as an abbreviation of the organisation’s name (eg WINGM is the unique code for the Gurkha Museum in Winchester). Exceptions to this are: London, where LD is used and this is followed by three letters for the institution. Some organisations wish to have a common code for all their museums (eg TWCMS for Tyne and Wear Museums). Some of the Nationals have kept their own codes (eg IWM for Imperial War Museum).

Why Use an MDA Code?

A MDA Code can be used together with an object’s accession number to uniquely identify that object, and link the object to its museum. The code can be used in the documentation (computer or paper-based) about the object. Ideally the code should be marked on all objects together with the accession number. However, some objects are too small and can only be marked with the accession number.

Further information is provided in the Spectrum Advice: numbering resource and the Spectrum Advice: labelling and marking museum objects resource.

Codes can be cited in publications, in correspondence, in work carried out by external agents (e.g. conservation or photography), and are useful when loaning objects. Having a unique code to identify your organisation is also very important when sharing data. Organisations are increasingly collaborating to put collections information online and MDA Codes are a simple way to provide a unique identifier for data about objects.

MDA Code Database

A database of current MDA Codes is available to browse and search.

Types of Code

An individual collection held by an organisation may have its own MDA Code, but this is very unusual. Possible reasons for this might be that the collection was, at some point in its history, held by another organisation that no longer exists.

It is possible for an organisation to change its MDA Code. This can be for various reasons. For example, the organisation may move its location or it may have been amalgamated with another organisation. However a change of MDA Code does not mean an organisation has to change its documentation or re-mark its objects.

How to get an MDA Code

To obtain an MDA Code please:

  • Search the MDA Code database to see if your organisation already has a code.
  • Check that your organisation has not changed names in the past and does not have a code based on any previous names.
  • If you have a code in mind please search the database to see if it is still available.
  • Once you have completed these checks please contact the Collections Trust to discuss possible codes for your organisation.

Having agreed a code the museum will need to write to the Collections Trust, on headed paper if possible, to confirm the code. The code will then be entered on the MDA Codes database.

Sources of help and advice

Documentation: a practical guide

Fact sheet

MDA Codes are defined in the Collections Trust MDA Codes fact sheet. The fact sheet also explains how and why to use them along with details of the MDA codes database as outlined on this page.


Clicking the link on this page will allow you to download this information as a PDF.

Date created: 2016

Author: Collections Trust

Publisher: Collections Trust