The bibliography 
                  section element represents a major structural division of a 
                  
                     bibliography
                     .
                  
               
The bibliography 
                  section element is a specialization of the 
                  
                     section
                      element that provides a content model to fit the unique requirements of bibliographic divisions.
                  
               
 The republishing of documents often requires the insertion of content that was not a part of the original source document.
                  For example, in the case of indexes, bibliographies and other ordered sections, this requirement may take the form of placeholder
                  sections to mark gaps in the alphabetic list of entries. To indicate that an element presents content that is a deviation
                  from the source, the 
                  
                     role
                      attribute can be used with the value 
                  custom. No behaviors are defined for how a processing agent should handle sections so identified, however.