It's hard to believe that metadata has a dark side, but it does. Conceived to shed light on data, metadata categorizes information to make it easier to track and find. But it also makes it easy for others to find out details about you and your documents. This reality became apparent when metadata was used to trace the authorship of a British security document justifying the war in Iraq to somewhere outside Great Britain.

The dark side of metadata has been known for some time. Microsoft has written extensively about how to remove metadata from Word documents going back to Office 97 products. Word automatically saves personal information, maintains hidden text of previous corrections and holds on to the names of previous authors. Word is not alone--many applications maintain metadata.

Internet filters can't help. Usually they look only for viruses, and metadata has not been classified as a virus yet. Even if your filters are looking for sensitive data by keyword in e-mail transmissions, they won't find it in attachments and their metadata. Only a special application like Workshare Metawall can do that.

The Brits' solution was to banish Microsoft Word from the kingdom. Another solution might be to learn the force of your applications, promote their positive sides and limit their dark sides.

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