خيار البلوغ
The option associated with reaching puberty.
In specified historical Hanafi marriage scenarios involving a marriage contracted during minority by a guardian, an option to seek dissolution could arise upon reaching puberty. The marriage had a legal effect before the later option arose; the option concerns continuation of that pre-existing effect.
This is not a universal claim that every marriage contracted during minority gives an identical option. The guardian's status, contract and conditions matter. The doctrinal point is that a subsequently arising right can affect the persistence of a previously established ruling.