sppp(4) on OpenBSD
The text 261bfc3a58e6, as OpenBSD 7.0, OpenBSD 6.9, OpenBSD 6.8, OpenBSD 6.7, OpenBSD 6.6, OpenBSD 6.5, OpenBSD 6.4, OpenBSD 6.3, OpenBSD 6.2, OpenBSD 6.1, OpenBSD 6.0, OpenBSD 5.9, OpenBSD 5.8, OpenBSD 5.7, OpenBSD 5.6 shipped it.
PPP and Link Control Protocol