I could not find any answer. But what I have understood is; if you are storing the files on the file system XOG out will only create a copy of the existing file structure. So, you do not need to XOG out if you are storing files in the file system instead of DB. in my case I am moving attachment from idea to project and reading from filestore directory.
Also my naming requirement is solved by file version Id. When Xoging in, PPM finds the file with version id the its own folder sturucture if you give the filestore directory for parent tag in the xml.
Regards