After MacOS X 10.1 when a new load command is added that is required to
be understood by the dynamic linker for the image to execute properly the
LC_REQ_DYLD bit will be or'ed into the load command constant. If the
dynamic linker sees such a load command it it does not understand will
issue a "unknown load command required for execution" error and refuse to
use the image. Other load commands without this bit that are not
understood will simply be ignored.
After MacOS X 10.1 when a new load command is added that is required to be understood by the dynamic linker for the image to execute properly the LC_REQ_DYLD bit will be or'ed into the load command constant. If the dynamic linker sees such a load command it it does not understand will issue a "unknown load command required for execution" error and refuse to use the image. Other load commands without this bit that are not understood will simply be ignored.