Internal documentation is what we, in our organizations, know about how our process works. Ops organizations have a long history of documentation that is written by sysadmins, for sysadmins. In larger organizations, these may be compiled by a writing team into more structured form. But that tribal knowledge is often only hard-won from practitioners themselves. In an organization whose core business is not the making of tech products, those docs may never be seen outside the technology group.