四分律行事鈔資持記 3.443

3.443

次科。作證明者，即上五中第二義也。論中約人有無以明成不；非畜成者，必約知解。

The next heading: "acting as a witness" is the second meaning among the five above. In the treatise, it explains validity or invalidity according to the presence or absence of humans; that non-humans and animals can effect validity must be based on their having understanding.