Disclaimer: This translation does not guarantee complete accuracy, please confirm with the original page text.
In the present chapter of the Vyavahar Sutra, only the second and third praharas of the day and night should be understood as the Vyatikrushta Kala, meaning that the study of the Kalik Sutra is prohibited during these four praharas. The Nandi Sutra states that the number of Kalik Sutras is 12 + 30 = 42, and the number of Utkalik Sutras is 29. The Anuyogadwar Sutra refers to the Aavashyak Sutra as Utkalik. Thus, a total of 42 + 30 = 72 Agam Shrutajnana are mentioned. The study of the available Kalik Sutras in the Utkal is prohibited in the first Sutra, but the second Sutra provides an exception for Sadhvis to study near Nirgranthas. The reason for this is that sometimes, it becomes necessary for Pravartinis or Sadhvis to listen to the original text from Upadhyayas, etc., so that the tradition of the original text remains consistent among other Sadhus and Sadhvis. The time for mutual study and recitation of Agams by Sadhus and Sadhvis is suitable only in the second and third praharas, hence this concession is given, it should be understood. The study of Utkalik Sutras in the four Sandhyakalas is also prohibited, therefore, the study of Dashakalik or Nandi Sutra cannot be done in the Sandhyakalas or at noon. In some traditions, the study of fifty gathas of the Nandi Sutra and two chulikas of the Dashavaikalik is done even during the time of Asvadhyay. Regarding this, it is believed that these compositions are not original. They have been added by someone other than the author. But this belief is erroneous and inappropriate, because the author of the Nandi Sutra is Devvachak Shri Devadhiggani Kshamasraman, this is undisputed. Devvachak is his epithet. The charnikar and tikaakar of the Nandi Sutra have accepted Devvachak or Devadhiggani as the author of the Nandi Sutra. Even in the 50 gathas of Nandi, at the end, Dushyagani is praised by bowing to him. Therefore, Devvachak Shri Devadhiggani, the disciple of Dushyagani, is the author of the Sutra. In the last verse of the last verse, it is said, "Naanas paruvaan vochch" = Now I will describe the form of knowledge. This also makes it clear that the author of Nandi is also the author of the 50 gathas. Therefore, it is not evidence-based to consider the 50 gathas as being added by someone other than the author of the Sutra, and it is completely inappropriate to study or recite the 50 gathas of the Nandi Sutra in the Sandhyakalas or during the time of Asvadhyay. Regarding the chulikas of the Dashavaikalik Sutra, there is a fictional story or legend that "these chulikas were brought by the sister of Sthuli Bhadra from the Mahavideha region." But the authenticity of this story is also doubtful. Because some texts mention the bringing of two chulikas, while others mention the bringing of four chulikas. -~-Parishista Parva, Parva 9, Aav. Chu. Page 188