This extension defines a feature, LV2_Log_Log, which allows plugins to print messages to logs implemented by the host with an API much like the standard C printf functions. This allows, for example, plugin logs to be nicely presented to the user in a graphical user interface. Different log levels (e.g. error or information) are defined by URI and passed as an LV2_URID. Thus, the possible number of log levels is unlimited, but implementations SHOULD use the levels defined in this extension unless they have a special reason to do otherwise.
A log level. Subclasses of this class can be passed to LV2_Log_Log methods to describe the nature of the log message.
A feature which plugins may use to log messages. To support this feature, the host must pass an LV2_Feature to LV2_Descriptor::instantiate() with URI LV2_LOG_LOG_URI and data pointed to an instance of LV2_Log_Log.