As in āhvāna आह्वान - Invocation
火字門，入諸法喚不可得故
The syllable HVa is a gateway because the appellation of all dharmas cannot be attained.
- Kumarajiva
入嗑縛字門，悟一切法可呼召性不可得故
The syllable HVa is a gateway because one realizes that name-ability of all dharmas cannot be grasped.
- Xuanzang
HVA because true appellations (āhvāna).
- Conze
The syllable HVA [means] all mental phenomena are openings because of the non-recognition of the invocation (āhvāna).
- Jayarava