.ACCDR File Extension
File TypeAccess Runtime Application
What is an ACCDR file?
"Locked-down" database file created by the Microsoft Access relational database software; stores an .ACCDB database, except with the extension renamed to ".accdr;" allows the database to be opened and run in a read-only mode so that no changes are made to the database.
If you want to run an ACCDB database in read-only mode, rename the file extension to ".accdr" and then open it. To restore the database to its original read-write format, rename the extension back to ".accdb."