Ordnance Survey of Northern Ireland produced mapping data that is amongst the most detailed and comprehensive in the world and, in 2005, has began to digitize the complete set of historical maps dating back to the 1830s together with another archival institution.
The vast majority of OSNI's income came from the licensing of its digital mapping data, which, because of the long history of mapping in Ireland (see Ordnance Survey) is amongst the most detailed and comprehensive in the world. In 2005 OSNI began, with the Public Records Office of Northern Ireland (PRONI), to digitise the complete set of historical maps dating back to the 1830s. The Public Record Office of Northern Ireland is distinguished from other archival institutions in the United Kingdom by its unique combination of private and official records. 
