Определение semi-official в Английский Язык Английский Язык словарь
Describing something, like a policy or opinion, which has some but not all of the authority of an official body. Such is thus probably correct but the body can change its mind (opinion or policy) without contradicting itself
Bearing some but not all the power of being official. As a semioffical opinion that is offered as probably correct and accurate but may be overturned on review and replaced by an official statement