Overt case change does not require changing the root letters of a name.
زَيْدٌ، زَيْدًا، زَيْدٍ
Translation: the same name with three different case endings.
The consonants of Zayd are unchanged; the ḍamma, fatḥa, and kasra differ. Unvowelled writing may conceal these differences, but they are still real case endings.
Do not conclude that a noun is indeclinable or has estimated case merely because an unvowelled text looks unchanged.
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The Rule of the Muʿrab: Visible and Estimated Case
Overt case change does not require changing the root letters of a name.
زَيْدٌ، زَيْدًا، زَيْدٍ
Translation: the same name with three different case endings.
The consonants of Zayd are unchanged; the ḍamma, fatḥa, and kasra differ. Unvowelled writing may conceal these differences, but they are still real case endings.
Do not conclude that a noun is indeclinable or has estimated case merely because an unvowelled text looks unchanged.