This report aims to provide practical guidance to less experienced organisations on the use of code lists. 

The SEMIC action has previously delivered extensive work in and around the development, maintenance, management, and governance of data specifications. In order to better support public administrations in their interoperability and information governance and management efforts, this document aims to act as a guide to developing or managing and consuming reusable code lists.

This deliverable builds upon the work previously carried out by the SEMIC action and included in “Methodology and Tools for Metadata Governance and Management for EU Institutions”.

What are code lists?

Code lists are lists of values in a predefined set that can be used in metadata and that help metadata creators in selecting from a set of descriptors, thereby enhancing consistency and helping to avoid errors. 

Code lists can be implemented using several technologies, in particular XML and RDF. In the case of RDF, code lists are usually called ‘controlled vocabularies’. Wherever necessary, the specific approaches related to implementation in XML and RDF are explained.

The use of code lists is an essential part of document alignment and data harmonisation. Many documents used in information exchanges require information about location, currency, dates, measurements, etc. The way this information is represented commonly differs in more or less subtle ways between countries and languages, despite being the same. IT systems therefore could either misunderstand this information, or not process it at all. The solution to this ambiguity is to have the information coded, creating an unambiguous way of representing it. Code lists minimise errors and reduce ambiguity, providing an essential contribution to interoperability.