Derwent Innovations Index (DII) is a comprehensive database of international patent information, merging records from the Derwent World Patents Index® with patent citation information from the Derwent Patents Citation Index® (Derwent PCI). The index provides web access to over 14 million basic inventions and more than 20 million patents, with coverage dating back to 1963 in some technology areas. The database gives users a comprehensive overview of inventions in the global marketplace in three categories: Chemical, Engineering, and Electrical & Electronic. The bibliographic records are enriched by citation data from Derwent PCI appearing in patents from 6 major patenting authorities. Derwent DCI provides details of citations, both patent and literature, reviewed by the examiner during the examination of a patent application. Prior to May 1997, examiner and author citations were provided for 16 patent-issuing authorities. The database also contains a backfile with patent records dating back to the 1970's. Every week approximately 25,000 patent documents from more than 47 patent-issuing authorities are reviewed and value enhanced by Derwent's patent experts. In addition, every week new cited and citing references are added for approximately 45,000 records from the six major patent-issuing authorities. The resource also includes Derwent Chemical Reactions (DCR), a unique database of searchable chemical structures and other substance-based information. It is used to search for specific compounds that are indexed in Derwent World Patents Index records.