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                             EXHIBIT A

          Pursuant to Rule 13d-1(f)(1)(iii) of Regulation 13D-G of the
General Rules and Regulations of the Securities and Exchange Commission
under the Securities Exchange Act of 1934, as amended, the undersigned agree
that the statement to which this Exhibit is attached is filed on behalf of
each of them.

Dated:  February 11, 2000     APERTURE ASSOCIATES, L.P.

                              By:   Horsley Bridge Partners, Inc.
                              Its:  General Partner


                                    By:   /s/ Phillip Horsley
                                          ------------------------
                                          Phillip Horsley
                                    Its:  President


                              HORSLEY BRIDGE PARTNERS, INC.


                              By:   /s/ Phillip Horsley
                                    ------------------------------
                                    Phillip Horsley
                              Its:  President


                               APERTURE PARTNERS, L.P.


                              By:   /s/ Phillip Horsley
                                    ------------------------------
                                    Phillip Horsley
                              Its:  General Partner


                                    /s/ Phillip Horsley
                                    ------------------------------
                                    PHILLIP HORSLEY


                                    /s/ Gary L. Bridge
                                    ------------------------------
                                    GARY L. BRIDGE


                                    /s/ N. Dan Reeve
                                    ------------------------------
                                    N. DAN REEVE