大般涅槃經義記 6.16

6.16

上來七門是無性空。「無所有」者，見因緣相亦無所有名無所有空，此無相空。是以下言「如人無子名之為空，非是就子明無性空；亦如貧人，無物名空，非是就物明無性空。」

The above seven approaches are the emptiness of lack of nature. As for 'non-existence', seeing that the marks of causes and conditions are also non-existent is called 'emptiness of non-existence'; this is markless emptiness. Hence it is said below: 'Just as a person without a son is called empty, not that emptiness of lack of nature is clarified in terms of a son; and also just as a poor person without possessions is called empty, not that emptiness of lack of nature is clarified in terms of possessions.'