How to read a .dbd file?

Working on helping a friend bring an old business into the 21st century. Part of that effort is getting some data into a modern relational database from where it is today.

After looking at the web app and some of the files, I think this is an IMS database. Form action goes to a .ini file which contains the following variables and paths.

FILEDDB "{file_path}.dbd"
FILEDIC "{file_path}.dic"
FILEhdc "{file_path}.xht"
FILEHLI "{file_path}.xht"

Is this an IMS database? If so, what's the best way to read / export this data into a more usable format?