The words denoting time, being in the Accusative -2nd case, are optionally compounded with a word ending in the affix kta and the resulting compound is tat-puruṣa,
This rule applies when duration of time is not connoted by the compound, which is provided for, in the next aphorism. The word for कालाः does not mean here, as it would otherwise mean by Sutra I. 1. 68, the word- from काल but special words denoting काल.
As मासप्रभितश्चचन्द्रमाः 'the new moon,' (literally, the moon that has begun to measure the month). Similarly, अहस्सङ्क्रान्ताः, रात्रिसङ्क्रान्ताः applied to six Muhurtas (of 48 minutes each) which are called चर and अचर which sometimes occur in day time (in the summer month) and sometimes in the night (in the winter).,