use the GS as a basis for setting pay rates. Some positions in the excepted service use the grade designator "GG"—for example, "GG-12" or "GG-13". The GG pay rates are generally identical to published GS pay rates. The GS-1 through GS-7 range generally marks entry-level positions, while mid-level positions are in the GS-8 to GS-12 range and top-level positions (senior managers, high-level technical specialists, or physicians) are in the GS-13 to GS-15 range. A new GS employee is normally employed in the first step of their assigned GS grade, although the employer has discretion to, as a recruiting incentive, authorize initial appointment at a higher step (other agencies may place the employee at a higher grade). In most professional occupations, entry to mid-level positions are classified at two-grade intervals—that is, an employee would advance from GS-5 to GS-7, then to GS-9 and finally to GS-11, skipping grades 6, 8 and 10. Advancement between steps within the same grade Permanent employees below step 10 in their grade normally earn step increases after serving a prescribed period of service in at least a satisfactory manner. The normal progression is 52 weeks (one year) between steps 1–2, 2–3, and 3–4, then 104 weeks (two years) between steps 4–5, 5–6, and 6–7, and finally 156 weeks (three years) between steps 7–8, 8–9, and 9–10. However, an employee can be rewarded for outstanding work performance via a "quality step increase" ("QSI"), which advances the employee one step within grade regardless of time at the previous step. (When a QSI is awarded, the date of the QSI becomes the starting date for the next step increase, which (if future step increases are awarded on the normal progression) will shorten the overall time for an employee to reach the final step within a grade.) Advancement between grades Depending on the agency and the work description, a GS position may provide for advancement within a "career ladder," meaning that an employee performing satisfactorily will advance between GS grades, normally on an annual basis, until he(she) has reached the top GS grade for that job (which represents full performance). Advancement beyond the top grade (to either a specialized technical position or to a managerial position) would be subject to competitive selection. Not all positions, however, provide for such a "career ladder," thus requiring employees who seek advancement to consider other career paths, either within their agency or outside it.