entire Playboy Web site as Adult, Sexually Explicit, or Pornography.  They do not

differentiate between pages within the site containing sexually explicit images or text,

and for example, pages containing no sexually explicit content, such as the text of

interviews of celebrities or politicians.  If the  root  or  top level  URL of a Web site is

given a category tag, then access to all content on that Web site will be blocked if the

assigned category is enabled by a customer.  

In some cases, whole Web sites are blocked because the filtering companies focus

only on the content of the home page that is accessed by entering the root URL.  Entire

Web sites containing multiple Web pages are commonly categorized without human

review of each individual page on that site.  Web sites that may contain multiple Web

pages and that require authentication or payment for access are commonly categorized

based solely on a human reviewer's evaluation of the pages that may be viewed prior to

reaching the authentication or payment page.  

Because there may be hundreds or thousands of pages under a root URL, filtering

companies make it their primary mission to categorize the root URL, and categorize

subsidiary pages if the need arises or if there is time.  This form of overblocking is called

 inheritance,  because lower level pages inherit the categorization of the root URL

without regard to their specific content.  In some cases,  reverse inheritance  also occurs,

i.e., parent sites inherit the classification of pages in a lower level of the site.  This might

happen when pages with sexual content appear in a Web site that is devoted primarily to

non sexual content.  For example, N2H2's Bess filtering product classifies every page in

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