The official response says:
The UK Government champions open standards and interoperability through its eGovernment Interoperability Framework Version 6.0, 30th April 2004 (eGIF) and through the publication of its Open Source Software Policy which is available in the document “Open Source Software, Use within UK Government, Version 2.0, 28 October 2004”.
This and eGIF are available from www.govtalk.gov.uk. Where possible the Government only uses products for interoperability that support open standards and specifications in all future IT developments.
Italics added.
