Thanks for your reply, it was helpful... although I am still a little stuck. First, the document you linked talks about a /Developer folder, which doesn't exist on my system (I'm running macOS 13.1 with Xcode 14.2). However, there is a folder named /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer which I suspect is what the documentation is talking about because it contains an SDKs subfolder as mentioned by the documentation. There I see symbolic links named MacOSX13.1.sdk and MacOSX13.sdk that both point to the folder MacOSX.sdk. So that makes sense. However, following the directions in the documentation, I tried to set MACOSX_DEPLOYMENT_TARGET to 13.0 and SDKROOT to 13.1. I understand this to mean that the program may not load on any version of macOS less than 13.0, and that I would need to dynamically test for the presence of 13.1-specific APIs before I can use them. In actual fact, I don't need to do anything with 13.1-specific APIs (right now, anyway!), but I just wanted to see how it worked. When I say "I tried to set..." I mean that I modified the "Build Settings" for my external target in Xcode by adding two new user-defined settings for MACOSX_DEPLOYMENT_TARGET and SDKROOT. Unfortunately, when I tried to build, it failed immediately with the error "unable to find sdk '13.1'". I tried setting SDKROOT to 13.0 (since it didn't seem to complain about my use of 13.0 in MACOSX_DEPLOYMENT_TARGET), but then I got "unable to find sdk '13.0'". For good measure I also tried changing the setting to just 13, but that produced the same error message. I next tried to just remove the SKDROOT setting entirely, but I can't figure out how to do that! There is a "+" button for adding settings, but no "-" button for removing them. Just erasing the setting didn't work. I got "name cannot be empty." This all comes down to two questions: Why can't it find the SDKs? They appear to exist on my system. How does one remove a user-defined build setting in Xcode? Thanks!