t;open()</a>  function will be
         searched relative to this path.  Paths set using this method are
         additive, and specifying more than one will result in each specified
         directory being searched for database files.  
    </p>
      <p>
         If no database directories are specified, database files must be named
         either by absolute paths or relative to the environment home
         directory. See 
         <a href="../../programmer_reference/env_naming.html" class="olink">Ber