The Rendering with Radiance book mentions many resources that live in the lib folder, such as winxmit.cal, materials.rad, and ies_lib/*. However, these are not included in the latest distribution of radiance. I have found some of these by looking at the dead files in the CVS browser, of which the last commit suggests that it is distributed separately. Some, such as ies_lib/*, I have not been able to find.
Where can I find the distribution of these files?
I’m not sure about the winxmit.cal but the ies_lib and materials.rad files are probably part of the “auxiliary files” and not the main installation. You’ll know when you download the auxiliary files because it’s many more MB than just the basic installation. You can find it in the older source code package in the middle of this page (NB: this is no longer the usual download page and it’s not the latest release as the URL implies): https://www.radiance-online.org/download-install/radiance-source-code/latest-release