The Mountain View, Calif., search engine company officially became a member of the Washington-based ODF Alliance on Saturday, according to Marino Marcich, managing director of the group.

Google officials did not respond to a request for comment. But Marcich called Google's decision to join "a natural fit, given Writely's support for ODF and further indication of momentum behind ODF."

Writely is an online word-processing program acquired by Google in the spring. The still-in-beta product lets multiple users create and edit the same document in real time through their Web browsers. Along with other software-as-a-service (SaaS) applications, Writely is being touted by some as a possible long-term competitor to Microsoft Word. Google also recently launched an online spreadsheet program, Google Spreadsheets. That application does not support OpenDocument.

The ODF Alliance claims more than 240 members. Half are technology vendors, including founding members IBM, Oracle Corp., Sun Microsystems Inc., Red Hat Inc. and Novell Inc. The other half comprise government bodies, nonprofit groups and academic institutions, according to Marcich. Companies can join the alliance without donating money.

ODF is an open XML file format that was accepted by the International Standards Organization as a standard in May. It is being adopted by the state government in Massachusetts, and in Denmark and Belgium for official governmental use.