The 'four formless concentrations.' Four states of concentration which lead to rebirth in the four formless heavenly realms: （1） concentration on infinite space 空无边处; （2） concentration on infinite consciousness 识无边处; （3） concentration on nothingness and 无所有处 （4） concentration on neither perception nor non-perception 非想非非想处.［俱舍论、 T 1558.29.41a］