The verse uses al-mawlud lahu—the person to whom the child’s birth is attributed—in identifying the father and assigning the duty of provision.
The textbook distinguishes two aspects of the same language:
The financial obligation: the point for which the discourse was brought, thus ibarat.
The child’s paternal attribution: indicated by the expression without being the direct topic of the financial ruling, thus isharah.
The legal effect of an expression may be direct in one respect and consequential in another.