What is Apple doing with UUCP?

I have been looking into UUCP (Unix-to-Unix Copy , a very old network protocol) as a way of communicating with some Linux boxes that don't always have an internet connection. While doing so on my Macbook (with El Capitan), I found entries in my /usr/share/uucp/sys file for uucpsys1.apple.com and uucpsys2.apple.com. (You can also see these by running uuchk | less.) What is Apple doing with UUCP? I found this post on the Apple forums by someone who noticed a UUCP user, but no one came forward with an explanation, so I'm hoping someone here will know. I'm especially curious because /usr/share/* falls under System Integrity Protection in El Capitan, which means I'll need to set up a separate UUCP implementation if I want to use it for my purposes — but it also suggests that, if Apple's shipping OS X with a UUCP that only they can use, they must be using it for *something.* *ETA:* I've also found a launchd daemon at /System/Library/LaunchDaemons/com.apple.uucp.plist. It has Disabled in the plist, so it won't be run by default, but other daemons could enable it programmatically without altering the plist. I'm also intrigued to see that it's in /System/Library/LaunchDaemons/ (and thus subject to SIP) rather than /Library/LaunchDaemons/ — it adds to my hunch that it's something Apple is using (or maybe was using, as patrix comments), rather than just a miscellaneous *nix tool they happened to include.