gerunds

अ॒स्य मदे॑ पु॒रु वर्पां॑सि वि॒द्वाँ इन्द्रो॑ वृ॒त्राणि॑ अप्र॒ती ज॑घान। ६.४४.१४ (विदित्वा)

प्राक् लिटः कानच्-क्वसुः-प्रत्ययाभ्यां क्त्वार्थः सम्पाद्यते स्म।
पश्चात् क्त्वाप्रत्ययेन बोध्यते।
क्त्वाप्रत्ययस्य मूलम् अस्ति
तु-अन्त-धातूनां भावार्थकानां तृतीयाविभक्ति-रूपम्।+++(5)+++

Even early Vedic used to use Vedic perfect participle as a functional gerund,
which was later replaced by a proper grammaticalized gerund
formed from instrumental case of verbal nouns derived using ’tu’ suffix.

Its a participle, also used to convey the gerundive meaning in the Rigveda. Later replaced by the proper gerund विदित्वा.

Note that the gerund in -tvā́ is found in twenty-one times (apparently) in the R̥g-vedá in addition to thirty-five in -tvī́ and nine in -tvā́ya, but of course it does become much more common later.

• nikhil