Individual rates of pay may be governed by the structure in the form of a fixed rate for the job or by movement in the form of fixed increments up a scale (a fixed increment is a predetermined addition to an individual’s rate of pay that is related to service in the job). These may take place within a pay bracket with fixed minima and maxima in a graded structure or by progression through defined pay ranges in a pay spine (a series of incremental pay points extending from the lowest to the highest jobs covered by the structure within which pay ranges for the jobs in the hierarchy are established). Alternatively, pay progression within brackets or bands or within job family structures may vary according to individual performance, competence or contribution.