A library and a couple of utility programs for dealing with PP packed files.
All managed Linux workstations up to 18.04 bionic
module add mo_unpack.
You will then have the 'pack_pp' and 'unpack' binaries in your PATH.
According to the Iris docs it is BSD but I can't prove that.
Some online at https://puma.nerc.ac.uk/trac/UM_TOOLS/wiki/unpack.
This comes with shell scripts for compilation. They need editing to work on Ubuntu: change the shell to /bin/bash and reorder the link line so -lmo_unpack -lm are the last arguments when linking.