ectly.  In addition, a history <dfn>expansion</dfn> function
is available which provides for a consistent user interface across
different programs.

   <p>The user using programs written with the History library has the
benefit of a consistent user interface with a set of well-known
commands for manipulating the text of previous lines and using that text
in new commands.  The basic history manipulation commands are similar to
the history substitution provided by <code>csh</code>.

   <p>If the programmer de