zshcalsys(1) on macOS
The text b19a26267f3c, as OS X 10.9.5, OS X 10.9.4, OS X 10.9.3, OS X 10.9.2, OS X 10.9.1, OS X 10.9 shipped it.
zsh calendar system
The text b19a26267f3c, as OS X 10.9.5, OS X 10.9.4, OS X 10.9.3, OS X 10.9.2, OS X 10.9.1, OS X 10.9 shipped it.
zsh calendar system