Many filtering companies rely on analysing the text on webpages for keywords or trigger phrases in close proximity to each other.

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Many companies use filtering software, produced by companies such as SurfControl and WebSense, which uses a watchlist of sites and stops employees reaching any website on the banned list.

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But even with this new tool, YouTube's filtering makes media companies work too hard to find and delete their content from the site, argues Gregory Rutchik, the founding attorney of the Arts and Entertainment Law Group.

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Saleem is writing to Western technology companies that make filtering software to try to keep them from working with the Pakistani government on the project.

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The two previous years, the tech industry and some savvy Internet users fought similar bills that would have created new liabilities for Internet companies and led to filtering or review for much user generated content and comments.

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In analytics, he says, there are companies that offer software for things like curation, filtering, and other things.

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