.DAX File Extension
File TypePSP Compressed ISO Disc Image
What is a DAX file?
Compressed disc image format used by the Sony PlayStation Portable (PSP) device; contains a "dump" of the data from a PSP UMD disc in a compressed .ISO file; can be opened with UMDGen or another disc image utility.
PSP game data can also be dumped into a .CSO (compressed ISO) file, which is similar to a DAX disc image.