This directory contains code not authored by Facebook or covered by its CLA, that is subject to its own copyright (INRIA) and license (LGPL 2.1 with OCaml linking exception) terms.
In particular, it contains two files of the OCaml standard library, with a patch to add some functionality used by ocamlformat. This code is included as a temporary measure while the pull request to include this functionality in the OCaml standard distribution is under review.
See ocaml/ocaml#1229.