Good guess, but I think I found what it actually was: Toll-Free Bridging[1]. Basically how you can use many Core Foundation types and NeXTSTEP classes interchan

Good guess, but I think I found what it actually was: Toll-Free Bridging[1]. Basically how you can use many Core Foundation types and NeXTSTEP classes interchangeably, like CFLocaleRef and NSLocale. Never really had to use it myself, at least IIRC, but I was aware of the concept generally. But because I didn't answer by saying 'Toll-Free Bridging', I was done. [1]: https://developer.apple.com/library/archive/documentation/General/Conceptual/CocoaEncyclopedia/Toll-FreeBridgin/Toll-FreeBridgin.html https://developer.apple.com/library/archive/documentation/Ge...