In such a case, only where the true owner has actual knowledge thereof may it be said that the possession is open and notorious. Occupant must not be in possession subordinate to owner. A's possession apparently adverse in this sense. Hostility requirement should not be used as an invitation to inquire into subjective states of mind. Mistake is irrelevant.
Abandonment stops clock.
Interruption by true owner stops clock. Tacking between adverse possessors allowed if there is privity. Entry occurred prior to transfer. Hence, disability provision doesn't apply. Common law allows imitation and copying.