The CERL Thesaurus file has been created since 1999. It is maintained by the Data Conversion Group in Göttingen. The format is UNIMARC "inspired". It consists of three parts: places, imprint names (printers and publishers) and personal names (authors, editors, translators). The Thesaurus exclusively serves early printing, which in the context of the activities of the Consortium of European research libraries (CERL) means printing of the hand press book area, starting from the beginnings (1450) until round about 1830/40.