<DOCUMENT>
<TYPE>EX-99.A
<SEQUENCE>2
<FILENAME>ex-a.txt
<DESCRIPTION>EXHIBIT A
<TEXT>
                                    EXHIBIT A

         Pursuant to Rule 13d-1(k) 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 agrees that the statement to
which this Exhibit is attached is filed on behalf of each of them in the
capacities set forth below.


Dated: November 8, 2005                  By:       /s/ Kim M. Silva
                                               --------------------------------
                                                   Kim M. Silva

                                           Attorney-in-Fact for:

                                           SPO PARTNERS II, L.P.(1)
                                           SPO ADVISORY PARTNERS, L.P.(1)
                                           SAN FRANCISCO PARTNERS II, L.P.(1)
                                           SF ADVISORY PARTNERS, L.P.(1)
                                           SPO ADVISORY CORP.(1)
                                           JOHN H. SCULLY(1)
                                           WILLIAM E. OBERNDORF(1)
                                           WILLIAM J. PATTERSON(1)

                                           (1) A Power of Attorney
                                           authorizing Kim M. Silva to
                                           act on behalf of this
                                           person or entity has been previously
                                           filed with the Securities and
                                           Exchange Commission.

</TEXT>
</DOCUMENT>
