After the verb kram preceded by vi , the ātmanepada is used when it is preceded by pra and upa , both conveying the same sense; viz. that of 'beginning an action'.,
As प्रक्रमते भोक्तुम्, उपक्रमते भोक्तुम् 'he commences to eat' &c.
The prefixes pra and upa are synonyms, when they denote the commencement of an action.
Why do we say, \when they are synonyms.\ Witness the following पूर्वेद्युः प्रक्रामति अपरेद्युरुपक्रामति 'he goes during the first part of the day and he comes back during the latter part of the day.' Here in one case the sense is \to go,\ in another it means \to return.\
Why in the latter case of 'aparedyur upakramati' there is not Atmanepada by virtue of sutra 1.3.39 ante, as there is the upasarga upa here? The answer is that Rule 1.3.39 is not applicable, as that rule is limited by the condition of the sense of 'continuity' &c. while in the present sutra, that limitation is not applicable.,