Data storage
CA 2188154 C · Owner: British Telecommunications Public Limited Company · Inventors: Foulston, John Howard
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Each file in a computer system has associated with it a token. No user is permitted to update any file unless that user is the current token holder. Thus, in multi-sited computer installations where nominally identical files are held in several data stores only one, copy of the file is ever updated at any one time. Tokens can only be transferred from one user to another with the permission of the current token holder, and on transfer of a token the latest version of the file accompanies that token. Some nodes of a computer system may have read access to obsolete versions of a file but each node holding an obsolete file is notified of current file versions available.
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed April 12, 1995 and granted August 29, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended April 12, 2015.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 12, 2017.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.