This makes prescriptivism a universalist form of non-cognitivism or expressivism. Prescriptivism stands in opposition to other forms of non-cognitivism (such as emotivism and quasi-realism), as well as to all forms of cognitivism (including both objectivist theories such as moral realism, and subjectivist theories such as moral relativism).
For an illustrative example of the prescriptivist stance, consider the moral sentence "Murder is wrong". According to moral realism, such a sentence claims there to be some objective property of 'wrongness' associated with the act of murder. According to moral relativism, such a sentence simply claims that murder is disapproved of by society. According to emotivism, such a sentence merely expresses an attitude of the speaker; it only means something like "Boo on murder!" But according to prescriptivism, the statement "Murder is wrong" means something more like "Do not murder" — what it expresses is not primarily a description or an emotion, it is an imperative. A value-judgment might also have descriptive and emotive meanings, but these are not its primary meaning on a prescriptivist account.
Hare would allow utilitarian considerations to enter into such a formulation, but he would not base the formula or his ethical theory solely on a principle of utility. Hare believed that all of our ethical propositions ought to conform with logic.