How an OCI item does not affect Book value ?

Hey Guys,

Can someone please explain me that how an OCI item for example, Foreign currency translation gain does not affect the Book Value per share ? what my understanding here is that, this item will overstate NI (income statement) which ultimately added to Equity after paying dividends as (Reserves & Surplus) in Balance sheet…book value should overstate as well isn’t it ??

Book value = total equity. OCI and Retained earnings are both part of equity so increasing one at the expense of the other will not affect total value.