The feminine affixes ī and ā (ṅī and āp) diversely become short before the affix tva,
Thus अजाया भावः = अजत्वं or अजात्वं, रोहिणित्वं or रोहिणीत्वम् ॥ These are Vedic illustrations, no Names can be formed in त्व ॥,
त्वे च
Adhyāya 6 · Pāda 3 · Rule 64