File Extension SSX File Format IBM Rational XDE file SSX stands for IBM Rational XDE file. This was last updated in March 2012 By Margaret Rouse Browse File Extensions Alphabetically: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ask a Question. Find an Answer. Ask your peers a question about this file extension. Ask a Question How to get pax file into ZFS for unpaxing SQLRPGLE- Query Not fetching records in program OS/400 descriptions of files in Library QUSRSYS.