मुखप्रतिमुखे चैव ज्ञेये विविधसञ्ज्ञिते । वृत्तप्रतिमुखं च स्यादन्या यास्तु समासतः ॥ २१०॥
The Mukha and the Pratimukha are to be regarded as the Vivadha, and the Vṛtta appears in the Pratimukha and may also occur briefly in other limbs.
english translation