The description of sdw format expansion
The sdw file is a text document created with StarOffice Writer 5.0 or earlier (also known as “StarWriter”). StarOffice Writer is the word processor included with Sun Microsystem’s StarOffice suite. In addition, the file can also be opened with the OpenOffice Writer text editor.
It should be noted, that StarWriter documents created with StarOffice 6 or later use the sxw extension.