What is the Validity File?
For the reformed IPC, the International Bureau provides a so-called validity file for each new core and advanced level edition. The validity file contains complete information on the validity periods of all classification symbols ever used in the IPC, i.e. it contains information on what date a particular symbol entered into force and on what date the valid use of this symbol ended. If no such expiration date is given in the most recent validity file, the symbol is to be considered as valid for use. The validity file does not contain any information on the titles associated with symbols. However, it does give some more information for each symbol: it also indicates whether the symbol is to be used as indexing code or ordinary classification symbol, and it also provides an indicator for its association with the core or advanced level.
