Feminine tāʾ plus proper-name status: Ṭalḥah is a diptote.
Semantic femininity plus proper-name status: Zaynab is a diptote; qualifying non-foreign triliteral Hind with a silent middle letter allows both declensions.
Feminine alif maqṣūra or mamdūda: ḥublā and ḥamrāʾ are diptotes because feminine alif stands for femininity and its permanence together.
Method: identify the cause and condition first, then assign the correct nominative, accusative or genitive marking. The next level begins the book’s discussion of proper-name status.