(Package) file is a compressed installer used by the PS3 to deliver software, including digital games, updates, and DLC. : It acts like a

Put your files into a folder named exdata (all lowercase) on the root of that same USB drive.

Put your files in the root of a FAT32-formatted USB drive.

file is Sony’s proprietary digital distribution format, functionally similar to a installer.

: Digital packages are often more compressed than disc-based ISO files, saving storage space. The Necessity of RAP Files

When official PSN content is acquired and installed: