Form: SC 13D/A

Schedule filed to report acquisition of beneficial ownership of 5% or more of a class of equity securities

December 3, 2004

AGREEMENT PURSUANT TO RULE 13D-1(K)

Published on December 3, 2004



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: December 2, 2004



/s/ Kim M. Silva
----------------------------------
Kim M. Silva

Attorney-in-Fact for:

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

* 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.