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Ah, that's just the namespace name you define for your Python registered classes. Name it whatever you want, provide a major version number (just '1' is fine. You'd only increase it if your module is used by other projects, and you want to maintain the old API along with the new one).
Then in QML, to use it, you add an import line to make it accessible in your QML:
import com.library.name 1.0