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 JanssEn En@parc.xErox.com>.