A Link To File field may contain a link to an externally-stored file.
The Free Mobile Edition allows for one file to be stored. The Pro Mobile Edition allows an unlimited number of files to be stored.
When importing and exporting, the full pathname to the file is used.
The file is not stored in the database. If files have been moved to another location, you can automatically change the links: library > right slide menu > files> menu > find missing files.
You can set the directory for files : settings > file storage.