An oop file extension is related to the OOP Packer and used for its archives.
OOP file extension - OOP Packer archive
What is oop file? How to open oop files?
File type specification:
The oop file extension is associated with OOP Packer, a data compression and archiving software for Microsoft Windows, developed by TonyTown Software Ltd.
The oop file contains archive created by OOP Packer.
This oop file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.