OPO (OPL Object, Psion OPL Output) is an executable format used on Psion PDA devices. OPO files are usually created by compiling programs written in the OPL programming language.
There is an OPA variant format, which can also contain embedded resource files. The embedded files usually include an icon in Psion PIC format.
The usual file extensions are .OPO and .OPA. We've observed .APP as well, though that's more commonly used for Psion IMG/APP format.
OPO and OPA files begin with the ASCII signature "
- http://www.project-atlantis.co.uk/download.html → OPL Info (OPO executable that displays information about OPO executables)