Because your webfilter requires a higher class blacklist.
Welcome to Squidblacklist.org. We are the worlds leading publisher of blacklists tailored for web content filtering purposes. We are also the only commercial supplier of works tailored for use directly as Squid Native ACL Blacklists. But we also have alternate formats available, including standard format , blacklists for most content filtering apps and platforms, such as Dansguardian and Squidguard. We are a subscription based service. For access to the works we derrive of our blacklist database, become a member today, select a membership option below or navigate to the downloads section to find out more. Samples can be requested via email at firstname.lastname@example.org