CUSIP NO. 717131 106 Schedule 13D/A Exhibit 99.1 JOINT FILING AGREEMENT In accordance with Rule 13d-1(f)(1) of Regulation 13d of the General Rules and Regulations of the Securities and Exchange Commission under the Securities Act of 1934, as amended,...

CUSIP NO. 717131 106                      Schedule 13D/A


                                                             Exhibit 99.1

                             JOINT FILING AGREEMENT

         In accordance  with Rule  13d-1(f)(1)  of Regulation 13d of the General
Rules and  Regulations  of the  Securities  and  Exchange  Commission  under the
Securities Act of 1934, as amended, the undersigned agree to the joint filing on
behalf of each of them of this statement and any subsequent amendments thereto.

Date:  January 7, 1998




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ASTER S.A.


By:      /s/ XXXX XXXXXXX XXXXXXXX
         Xxxx Xxxxxxx Xxxxxxxx
         President



GES INVESTMENTS, S.A.


By:      /s/ XXXX XXXXXXX XXXXXXXX
         Xxxx Xxxxxxx Xxxxxxxx
         President