Form: 4

Statement of changes in beneficial ownership of securities

April 13, 2004


POWER OF ATTORNEY

STATE OF TEXAS
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COUNTY OF DENTON
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The undersigned, Ramon D. Phillips, does hereby constitute and appoint B. Keith Clark or Rod McDonald, as my true and lawful attorney and agent, in the name of and in my place and stead, to execute and file any and all Forms 4 required to be filed on my behalf, as fully and to all intents and purposes as I might or could do if personally present, with full power of substitution and revocation, hereby ratifying and confirming all that said attorney or substitute shall lawfully do by virtue hereof.

This power of attorney shall remain in effect until specifically revoked by signed writing.
Signed as of September 19, 2002.
 
/s/ Ramon D. Phillips
 

 
Signature
 
 
 
 
 
Ramon D. Phillips
 

 
Name Printed