Mike, the rating of "a" Normal, meaning "normal" is the same as a1. This is followed by "a" fast Normal (a2) which means "nearly normal" and finally by "a" noch Zugelassen (a3) which means "still certifiable". The S.V.'s rating system for elbows follows the same scheme. It is perhaps important to note that a slim majority of GSD's score as "a" Normal.
You did not ask - but I will say it anyway. The hip rating of an individual dog is important, but is only a part of the total package. Of great importance is the ZW (Zuchwert, or breed-worthiness) number earned by that dog as it reflects how his ancestors/siblings/other close relatives have fared with their individual hip quality. I will keep it short as it requires much typing to explain exactly how the ZW system works.
In short, the mean value for the ZW is 100. Dogs who score higher than 100 are at a higher risk to produce hip dysplasie, and dogs who score less than 100 are at a lower risk to produce hip dysplasie. The average of the sum of the ZW's for a breeding pair can not exceed 100. In other words, one could breed a male with a ZW 110 to a female who has a ZW that is not greater than 90, or of course vice-versa.
Provided the hips of both parents are evaluated by the S.V. and ZW numbers assigned to each; the offspring begin life with a ZW that is essentially the average of the parents. This number will remain the same, unless the offspring show better or worse hip quality than the parents when they are examined. If they "improve" their number may drop very slightly, but if they "worsen" their number will rise slightly. If one is found to be dysplastic then the numbers can rise significantly. I am just using the parents and offspring as an example, but in reality all close and scored relatives affect the ZW for a dog.
Lastly, you may see a hip rating of "Zuerkannt" on older pedigrees. This shows that the hips passed the S.V.'s evaluation, but did so before the S.V. adopted the "a" stamp rating system that defined the quality of hips. This is similar to the years past when O.F.A. assigned "Normal" as their passing score, and later developed the grades of "Excellent", "Good", and "Fair".
This is essentially a brief explanation of what can be a lengthy subject to express in detail.
(edited last sentence of first paragraph; replaced "a" fast Normal with "a" Normal)