(a) “salary range” is the minimum and maximum rate currently authorized for the class;

(b) “step” is the difference between two salary rates one full salary range number apart;

(c) “rate” is any one of the salary rates in the resolution by the Department that establishes the salary ranges and steps of the pay plan;

(d) “range differential” is the difference established by resolution of the Department between two consecutive salary ranges of the pay plan;

(e) “substantially the same salary range” is a salary range with the maximum salary rate the same as or less than two steps higher or lower than the maximum salary rate of another salary range;

(f) “higher salary range” is a salary range with the maximum salary rate at least two steps higher than the maximum salary rate of another salary range; and

(g) “lower salary range” is a salary range with the maximum salary rate at least two steps lower than the maximum salary rate of another salary range. Any rate falling within the salary range for a class may be used to accomplish appropriate step differentials in movements between classes and salary ranges.