Natyashastra
मुखप्रतिमुखोपेतं तथा चञ्चूपुटाश्रयम् । यथाक्षरैः सन्निपातैस्तथा द्वादशभिर्युतम् ॥ ३२२॥
It should include gestures facing the front and the opposite (mukha-pratimukha), and be performed in the rhythm based on the Cañcupuṭa. It should be composed with corresponding syllables and contain twelve measures.
english translation
mukhapratimukhopetaM tathA caJcUpuTAzrayam । yathAkSaraiH sannipAtaistathA dvAdazabhiryutam ॥ 322॥
hk transliteration by Sanscript