If this option is set to true, all URLs returned from the MCFileManager will be relative from the specified document_base_url. This option is set to false by default.
Remember this option doesn't do much when using the MCFileManager as a TinyMCE plugin since TinyMCE does the URL convertion, consult the TinyMCE manuals for details on URL convertion.
Example of usage in init call on page level:
mcFileManager.init({ relative_urls : true });
Example of usage in mcFileManager.open call
<a href="javascript:mcFileManager.open('example1','url','','',{relative_urls : true});">[Browse]</a>