Hierarchical Knowledge Base file. This type of file uses a hierarchy of categories. Multiple levels of categories might be beneficial when similar concepts appear in more than one category. By grouping categories under a branch, it is easier to locate a specific solution associated with a category. The following code is a hierarchical knowledge base with two top-level categories: English and German. The knowledge base name is still KB, but now the five categories are repeated for each language.
<?xml version="1.0" encoding="UTF-8" ?> 
  <knowledge-base name="KB">
  <category name="English">
  <category name="apparel - English"/> 
  <category name="automotive - English"/> 
  <category name="baby - English"/> 
  <category name="beauty - English"/> 
  <category name="books - English"/> 
  </category>
  <category name="German">
  <category name="apparel - German"/> 
  <category name="automotive - German"/> 
  <category name="baby - German"/> 
  <category name="beauty - German"/> 
  <category name="books - German"/> 
  </category>
  </category>
  </knowledge-base>