Lowest set of locants - IUPAC system of nomenclature

while two or more substituents are present, then end of the parent chain that provides the lowest set of the locants is preferred for numbering. This rule is known as lowest set of locants. That illustrates that when two or much more different sets of locants are possible, that set of substitutes which when linked term by term along with other parts, each in order of increasing value, comprise the minimum term at the first point of difference. This principle is required irrespective of the nature of the alternative.