1 Preface
  
  This is one of the three main GAP books. It describes most essential changes
  from previous GAP releases.
  
  In  addition to this manual, there is the GAP Tutorial and the GAP Reference
  Manual  containing  detailed documentation of the mathematical functionality
  of GAP.
  
  A  lot  of  the  functionality  of  the  system  and a number of contributed
  extensions  are  provided  as  GAP  packages,  and each of these has its own
  manual. New versions of packages are released independently of GAP releases,
  and   changes   between   package   versions   may  be  described  in  their
  documentation.