A class is a set of particular generations of elements.
  You typically combine generations into classes to
  represent the state of elements at a particular time or
  stage.

  For example, you might create a class containing only
  those generations of elements that were used to produce
  the first draft of a manual in base level 1.

  A class name is a string of 39 or fewer characters that
  consists of letters, digits, underlines, hyphens, dollar
  signs, and periods.  Class names must begin with a letter.

  You can perform the following functions on classes:

  o  Create and delete classes
  o  Fetch, reserve, replace, review, and set an access
     control list (ACL) on the contents of a class
  o  Insert generations into a class
  o  Remove generations from a class
  o  Set or change the attributes of a class
  o  View the contents and attributes of a class