This reply follows Brian's question from 4 Jan 2013. Thanks Brian for this question. I have been reading earlier parts of the Paramatthajjotikā recently, so I enjoyed the chance to think about the beginning of the Cundasutta commentary. My understanding of the long compound attajjhāsayaparajjhāsayaaṭṭhuppattipucchāvasikabhedato is that it means: 'according to the division into (bhedato) (i) one's own disposition (attajjhāsaya) (ii) the disposition of another (parajjhāsaya) (iii) the situational meaning (aṭṭha-uppatti) or (iv) answering a question (pucchāvasika)'.
Hence the commentary is saying that the origin of this sutta (the Cundasutta) is answering the question, in reference to the four origins, which are analysed into: suttas taught on the Buddha's own initiative, suttas taught according to the inclination of the hearers, suttas taught according the present situation, and suttas taught in order to answer a question.
This division of the Buddha's preaching into kinds of origin is called the cattaro suttanikkhepā or fourfold summary of the suttas and found at e.g. D i.50. Also there is cattāro hi suttanikkhepā attajjhāsayo parajjhāsayo pucchāvasiko aṭṭhuppattiko'ti in the Buddhavaṃsa comm.
I expect you've worked all this out by now, but I've enjoyed working out for myself too.
Best wishes
Dhivan
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