lwres(3) on macOS
The text 3049ff4139d4, as Mac OS X 10.8.1, Mac OS X 10.8, Mac OS X 10.7.4, Mac OS X 10.7.3, Mac OS X 10.7.2, Mac OS X 10.7.1, Mac OS X 10.7 shipped it.
introduction to the lightweight resolver library
The text 3049ff4139d4, as Mac OS X 10.8.1, Mac OS X 10.8, Mac OS X 10.7.4, Mac OS X 10.7.3, Mac OS X 10.7.2, Mac OS X 10.7.1, Mac OS X 10.7 shipped it.
introduction to the lightweight resolver library