Trying to get current folder name from FileMaker

I want to show pdf files from an external harddrive.
The filemaker aplication is stored in that drive this way:
/Database
/Database/db.fp7
/Database/2004/file1.pdf
/Database/2004/file2.pdf

/Database/2005/file1.pdf

Also, as we do backups in diferent drives, drive name changes…
So the problem is to know how to open those pdf files in diferent subdirectories, from the db.fp7 application.
I’m trying to find out db.fp7 path

thank you,
Javier.