case                Label for multiple conditional branch
 do                  Obsolete function call statement, see ()
 do case             Multiple conditional branch start
 do while            Pre-conditional iterative execution start
 else                Default label for simple conditional branch
 endcase             Multiple conditional branch end
 enddo               Pre-conditional iterative execution end
 endif               Simple conditional branch end
 exit                Terminate loop
 for                 Iteration start
 if                  Simple conditional branch start
 loop                Restart loop
 next                Iteration end
 otherwise           Default label for multiple conditional branch
 repeat              Post-conditional iterative execution start
 return              Return control to calling code
 until               Post-conditional iterative execution end