IARs are registers specifically set up to capture and organise meta-data about the vast quantities of information held by government departments and agencies. A comprehensive IAR includes databases, old sets of files, recent electronic files, collections of statistics, research and so forth.

IARs can be developed in different ways. Government departments can develop their own IARs and these can be linked to national IARs. IARs can include information which is held by public bodies but which has not yet been – and maybe will not be – proactively published. Hence, they allow members of the public to identify information which exists and which can be requested. It is important that IARs are complete as possible because otherwise possible re-users could be discouraged from finding or requesting the dataset.

It is essential that the metadata in the IARs should be comprehensive so that search engines can function effectively. In the spirit of open government data, public bodies should make their IARs available to the general public as raw data under an open license so that civic hackers can make use of the data, for example by building search engines and user interfaces. The EU PSI Directive and the EU OD Directive require of Member states to establish tools that help re-users to find documents available for re-use, such as asset lists.

Source: ODH.