Pattern converters don't have the intelligence. I agree. However, converters don't exist for their own sake -- they exist for layouts and ultimately for Appenders. Those are the instances that have the intelligence to make sense out of themselves. Even more so is the Processor to make sense out of the configuration file.
Hence my original question: Does it make sense for a File Appender to emit "colors"? If it does, then okay, but I'd like to hear the concrete justification one way or another. I am interested in the purpose. Cheers and God bless, Paul