INterface SpecificatioN LaNguage. Xerox PARC. INterface descriptioN laNguage used by the ILU (INter-LaNguage UNificatioN) system. INcludes descriptioNs of multiple iNheritaNce, exceptioNs aNd garbage collectioN. E-mail: Bill JaNsseNNsseN@parc.xerox.com>.