佛祖統紀 3.20

3.20

五時立名不出三義。華嚴從喻。鹿苑從處。方等般若涅槃從法。法華從法喻。

The naming of the five periods does not go beyond three senses: Avataṃsaka follows metaphor; Deer Park follows place; Vaipulya, Prajñā, and Nirvāṇa follow Dharma; the Lotus follows both Dharma and metaphor.