Hello all, David Lloyd recently asked about SLF4J style parameter substitution, that is the {} convention over, the convention defined in java.text.MessageFormat. In fact, CAL10N uses the java.text.MessageFormat convention. See [1]. By extension, LogLogger in SL4FJ uses the convention adopted by CAL10N, i.e. the java.text.MessageFormat convention whenever enums are used, and uses the SLF4J convention when the message key is a String (instead of an enum). I hope this clarifies the matter. [1] http://cal10n.qos.ch/manual.html#retrieving -- Ceki Gülcü Logback: The reliable, generic, fast and flexible logging framework for Java. http://logback.qos.ch