After the verbs vṛt 'to exist' etc., parasmaipada is optionally used when the affixes sya (Future and conditional) and san (Desiderative) follow.,
The वृतादि verbs are five in number and are included in the द्युतादि sub-class. They are वृत् to be, वृध् to grow, शृधू to fart or break wind; स्यन्दु to ooze, and कृपु to be able. As Ist Future वर्त्स्यति or वर्त्तिष्यते, it will be; conditional अवर्त्स्यत् or अवर्तिष्यत्; Desiderative विवृत्सति or विवर्त्तिषते &c.
In other tenses than the above, they are always Atmanepadi. As वर्त्तते it is.,