Makefile.yp(8) on OpenBSD
The text 390627b3fdf4, as OpenBSD 5.8, OpenBSD 5.7, OpenBSD 5.6, OpenBSD 5.5, OpenBSD 5.4, OpenBSD 5.3, OpenBSD 5.2, OpenBSD 5.1, OpenBSD 5.0, OpenBSD 4.9, OpenBSD 4.8, OpenBSD 4.7 shipped it.
generate and distribute YP maps