This extension defines a feature, log:log, which allows plugins to print log messages 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. This document defines the typical levels which should be sufficient, but implementations may define and use additional levels to suit their needs.
A log entry. Subclasses of this class can be passed to LV2_Log_Log methods to describe the nature of the log message.
A debugging trace. These entries should not be displayed during normal operation, but the host may implement an option to display them for debugging purposes. This entry type is special in that it may be written to in a real-time thread. It is assumed that if debug tracing is enabled, real-time considerations are not a concern.
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 and data pointed to an instance of LV2_Log_Log.