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OpenSCD addons will be a replacement for current mixins, so there is no or less need to fork OpenSCD-core and to build mixins on top of the fork. Addons allow experiments with (potential) new core functionality. Succesfull addons can met merged into OpenSCD-core.
Example: Wizarding API is hard to make pefect in the first run. If started with an addon for wizarding, we can experiment/use. It it turns out that the addon is missing crusial functionality. We can introduce a new add-on next to the old addon (with its limitations).
What are mixins: TypeScript: Documentation - Mixins (typescriptlang.org)
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