The FCC has authorized the Maxim Memorial Station W1AW to also use the call sign W100AW during 2014, the ARRL's centennial year.
Contacts made from the Maxim Memorial Station in Newington, from regional Centennial conventions, and during the IARU HF Championship will use W100AW, with portable designators as appropriate.
The "W1AW WAS" operations throughout 2014 from each of the 50 states will use W1AW, not W100AW.
Bulletins and code practice transmissions during 2014 also will still use W1AW. Contacts with W100AW are worth 100 points in the ARRL Centennial QSO Party.
ARRL Centennial QSO Party - http://www.arrl.org/centennial-qso-party