A reservation is «a unilateral statement, however phrased or named, made by a State, when signing, ratifying, accepting, approving or acceding to a treaty, whereby it purports to exclude or to modify the legal effect of certain provisions of the treaty in their application to that State» (See Article 2 of the Vienna Convention)
If a book is being borrowed by another person, you may reserve the book, so that when it is returned it is put aside for you to collect at the Issue desk
{i} misgivings that bring about hesitation, doubts that prevent sincere approval of something