Whether the plugin should be not selectable in the UI. If it's set to TRUE, you can still use it via the API in config files.
The types of the display this plugin can be used with. For example the Feed display defines the type 'feed', so only rss style and row plugins
The plugin title used in the views UI. Type:
(optional) The short title used in the views UI. Type:
The plugin ID. Type: string File core/modules/views
Defines a Plugin annotation object for views exposed form plugins. Hierarchy class
A short help string; this is displayed in the views UI. Type:
The base tables on which this exposed form plugin can be used. If no base table is specified the plugin can be used with all tables.