SPECIAL POWER OF ATTORNEY

THE STATE OF VIRGINIA

COUNTY OF
ARLINGTON

KNOW ALL MEN BY THESE PRESENTS:

THAT I, ROBERT B.
BUCKNAM, of 3400 N. Woodrow Street, Arlington, VA 22207, do hereby appoint
each of Kent H. Roberts, Stephen C. Richards and Jennefer Koopman, or any
of them acting individually, my true and lawful attorney-in-fact to act in
my name, place and stead and on my behalf to do all or any of the following
acts, deeds and things, to-wit:

	To prepare, sign and file Forms 4 and
Forms 5 with the Securities and Exchange Commission.

This instrument
is to be construed and interpreted as a special power of attorney, whose
scope is limited to that referenced immediately above.

IN WITNESS
WHEREOF, I hereunto set my hand this 22nd day of May, 2003.


/s/
Robert B. Bucknam