After the word putra the affix cha (īya) also comes, as well as yat (ya), in the above sense of 'a relation or a portent for the purpose of that'.,
The word पुत्र being a dissyllabic word would always have taken यत् by the last aphorism. This ordains छ also. Thus पुत्रस्य निमित्तं संयोग उत्पातो वा = पुत्रीयम् or पुत्र्यम् ॥,