A type of ākāśaśreṇi (Śreṇi (1) (row of space-units through which the motion of soul and physical substance takes place);
that Śreṇi which is straight and long; when the place of departure (death of soul) and that of arrival (new birth of the soul) (or the places of departure and destination of the Pudgala) are in the same straight line (Śreṇi), while going from the upper cosmos to the lower one or the vice-versa, the Jīva or the Pudgala will travel along this Śreṇi, without taking any turn; it would take only one Samaya (smallest time-unit) to reach the point of arrival.
'ujjuyāyata' ti ṛjuścāsāvāyatā ceti ṛjvāyatā yayā jīvādaya urdhvalokāderadholokādau ṛjutayā yāntīti.
(Bhaga 25.91 Vṛ Pa 865)
'ujjuayayāe' tti yadā maraṇasthānāpekṣayotpattisthānaṃ samaśreṇyāṃ bhavati tadā ṛjvāyatā śrenirbharvati.
(Bhaga 34.2 Vṛ Pa 956)