As in च्यवन - cyavana (’declining’)

左字門一切法離一切遷變故

遮字門一切法終不可得故，諸法不終不生故 

入者字門，悟一切法無死生故 (Xuanzang)

入者字門，悟一切法遠離死生，若死若生皆無所得為方便故 (Xuanzang, 18,000 lines)

'CA' is a gateway because all dharmas are free of decreasing (cyavana च्यवन ) their decreasing cannot be found

CA is a door to the insight that the decease (cyavana) or rebirth of any dharma cannot be apprehended, because all dharmas do not decease, nor are they reborn.

Conze

The syllable ca is an opening because of the non-perception of the causes of

falling (cavana) of any mental phenomena.

Jayarava