ELSEIFB          ELSE With IFB                                      Directive

  ELSEIFB <argument>

     This directive is the same as an ELSE followed by an IFB. (IFB is
     satified if argument is blank.) It is used to start a nested
     conditional block. For example:

                        IF NUMBER EQ 5
                           add ax,3
                        ELSEIFB NUMBER
                           add bx,2
                        ELSE
                           add cx,1
                        ENDIF

       Notes:     See ELSEIF and IFB for more information.