Natyashastra
किञ्चिदञ्चितजङ्घं च सौष्ठवाङ्गपुरस्कृतम् । वैष्णवं स्थानमेतद्धि विष्णुरत्राधिदैवतम् ॥ ५३॥
The shank should be slightly bent (añcita), and the limbs should be well-aligned with grace (sauṣṭhava). This is the Vaiṣṇava Sthāna, with Viṣṇu as its presiding deity.
english translation
kiJcidaJcitajaGghaM ca sauSThavAGgapuraskRtam । vaiSNavaM sthAnametaddhi viSNuratrAdhidaivatam ॥ 53॥
hk transliteration by Sanscript