Types of Plugins based on level of integration in Grails

Some quick notes on distinctions between Grails plugins. One useful cut is by how integrated the plugin is into Grails. There are the following levels of integration that I see from most to least integrated:

1. Internal Core plugin: this type is part of the Grails core build. Loaded statically at startup by CorePluginFinder
2. External Core plugin: maintained as part of the Grails distribution but installed using scripts and opt-in. See Grails plugins for list.
3. Supported plugins: Superset of the external core plugins that is maintained by SpringSource.
4. Central repository plugins: grab-bag of plugins that are maintained according to a loose set of conventions and accessed via a list at Grails.org
5. User repository plugins: plugins that are accessed via a user repository specified in BuildConfig.
6. Local plugins: plugins that are accessed using "grails.plugin.location"