Libraries are directories in specific locations in your STEAM folder and they are displayed in the “Directory” menu in Omnisphere’s browsers. The folders inside libraries are displayed as Categories.
In order to create a library, you must create a directory using the Finder (Mac) or Explorer (Windows). Patches, Multis, and Soundsources are located in separate directories in your STEAM folder. If you wish to publish a library that includes Patches and Multis, the libraries where those Patches and Multis are located must have the same name. User Soundsources used by any Patch or Multi in the library you want to publish will be automatically added to the .omnisphere package, so there is no need to create a Soundsource library with a matching name.