ma is optionally substituted for the niṣṭhā ta after the root stayai preceded by pra,
Thus प्रस्तीमः or प्रस्तीतः, प्रस्तीमवान् or प्रस्तीतवान् ॥ In the second alternative when म does not come, we first vocalise the root स्त्या into स्ती, and then add त ॥ Had samprasarana not taken place first, then the Nishtha त would have been changed to म after स्त्या by 8.2.43. But when samprasarana is once made, the root no longer has a semi-vowel and so there remains no occasion for the application of 8.2.43. See 6.1.23 for vocalisation.,