It　is　often　explained　in　textbooks　that　the　synthetic　expression　method　（synthesis　ofnotation　by　auxiliary　tables　or　other　parts　of　the　schedule）　of　the　Dewey　Decimal　Classification（DDC）　is　a　device　for　treating　complex　subjects．　However，　such　an　explanation　is　wrong　andbased　upon　a　confusion　of　the　“synthetic　expression　method”　for　notation　system　with　the“analytico－synthetic　procedure”　for　subject　structure．　The　analytico－synthetic　procedure　is　aprocedure　for　applying　division　principles　to　subjects　specific　to　classification　systems　withmulti－dimensional　structure　such　as　Colon　Classification．　While　division　principles　are　to　beapplied　in　due　order　in　the　hierarchical　structure，　they　can　freely　be　applied　in　the　multidimensional　structure．　Therefore，　complex　subjects　can　easily　be　classified　and　thus　bettertreated　in　the　latter　structure．　Also，　it　is　true　that　most　classification　systems　with　the　multidimensional　structure　have　adopted　the　synthetic　expression　method　for　their　notation　systems．　However，　the　subject　structure　is　in　principle　nothing　to　do　with　the　notation　system　ofa　classification　system．　Any　subject，　which　can　be　expressed　by　the　synthetic　expressionmethod，　can　also　be　expressed　by　the　enumerative　method．　Therefore，　the　synthetic　expressionmethod　of　the　DDC　cannot　be　an　effective　device　for　treating　complex　subjects　（as　comparedwith　the　enumerative　expression　method）．