The Libra Framework is a Move language framework that can run on Diem Platform nodes. It contains the policies for the $LIBRA asset and the Open Libra Network.
For the Open Libra network members, who are very opinionated about policies and economics, the majority of the community's innovations are found here.
Move frameworks are source code written in the Move Language. In Diem Platform (and in vendor versions), the framework contains almost all of the platform's business logic: account creation, coin minting, asset transferring, code publishing, code upgrades, selecting validators, etc.
There are many tools needed for the framework to be properly developed, installed, upgraded, transacted with, monitored, etc.
There isn't any code regarding database, consensus, networking, virtual machines, etc. here. That code belongs in Diem Platform. There are many vendors of the Diem technologies, and Open Libra maintains a version with linear commits back to Facebook's version, and updates it with maintenance upgrades from contemporary vendors.
In general, we have a light touch approach with our upstream dependencies. We optimize for clean APIs that easily pull in libraries from vendors. Ultimately, the Open Libra members are agnostic about blockchain technology, so long as it has the necessary components for the mission of $LIBRA.
Core Devs should start here.