大毘盧遮那經廣大儀軌 2.143

2.143

左白蓮華中，觀𠻱字光輪，
轉成虛空慧。印如轉法輪。

In the white lotus on the left, visualize the light-wheel of the syllable haḥ,
which transforms into Gaganamati;
the mudrā is like the wheel of turning the Dharma wheel.