PluginRootDirSymbol is the name of a variable of type string which a plugin may define if it want to obtain the plugin root directory.

PluginSymbol is the name of a variable of type plugin.Plugin which all plugin implementations MUST define.

Manifest is the plugin manifest, stored as a data object in the plugin SIF.

Plugin is the "meta-type" which encompasses the plugins implementation through Callbacks and a Manifest (potentially more to be added).

Callback defines a plugin callback.