"[...] The Strasbourg Agreement (of 1971) concerning the International Patent Classification provides for a common classification for patents for invention including published patent applications, utility models and utility certificates. The International Patent Classification (IPC) is a hierarchical system in which the whole area of technology is divided into a range of sections, classes, subclasses and groups. The Classification is periodically revised in order to improve the system and to take account of technical development. The current, seventh, edition of the IPC will be in force until December 31, 2005. The next, eighth, edition of the IPC will enter into force on January 1, 2006. [..]"
The IPC 8th Edition will now provide a two level system comprising a relatively simple and stable core level, and a more complex dynamic advanced level. Moreover, there will be the addition of an electronic layer with more than 3000 illustrating chemical formulae.
A guide is available on-line at the website of the WIPO.