Some systems will store a 'link' to the document which would be
stored on your servers, rather than storing the actual document within an entry in the database.
By saving a text link, rather than the document, the actual file or record is accessible even if you
change systems in the future. As long as you have some way to extract the link text from any database files and a way to possibly change it to a new location, the link would work with a future system. In this way the original file remains untouched through any software replacement.