وَيُطْلَبُ بِـ«مَنْ» الْعَارِضُ الْمُشَخِّصُ
Man seeks an individuating attribute or description.
مَنْ فِي الدَّارِ؟
Who is in the house?
The answer may be 'Zayd,' since the question requests the identity of the person present. The location is already understood; the missing information is the person's identity.
An individuating description need not be an essential definition. A familiar name, distinctive description or other identifier can adequately identify the intended individual.