开始用openoffice(2.4.1)了，Calc默认的扩展名是ods.

ODS: OpenOffice/StarOffice Software ?

This file format is part of the Open Document Format for Office
applications (OpenDocument) 1.0 specification. This OASIS format is
expected to become an industry standard for sharing documents. It is
being adopted by the OpenOffice/StarOffice version 2 software suite but
may appear in other products as well.