छन्दसि पुनर्वस्वोरेकवचनम्

In the Vedas, the star punarvasu which is always dual in form, may be in the singular form and connote a dual meaning. As पुनर्वसुर्नक्षत्रं or पुनर्वसू नक्षत्रमदितिर्देवता ॥ The option is only allowed in the Vedas and not in secular literature. In the latter it must be in the dual, that is, पुनर्वसू ॥ Similarly when it is not the appellation of an asterism but of a man, there is no option. As पुनर्वसू माणवकौ.,