EXHIBIT 23.1
Published on March 29, 2001
EXHIBIT 23.1
Consent of Independent Public Accountants
As independent public accountants, we hereby consent to the incorporation of
our report included in this Form 10-K, into the Company's previously filed
Registration Statements on Form S-8 No. 333-16837, on Form S-8 No. 333-56089,
on Form S-3 No. 333-87063, on Form S-3 No. 333-15407, on Form S-3
No. 333-62855, on Form S-3 No. 333-60875 and on Form S-3 No. 333-87219.
/s/ Arthur Andersen LLP
Vienna, Virginia
March 27, 2001