I hate to throw a wrench into this; but, I had my career military Navy husband look at the records.
He figured out that the SVC was the date it took to make the member's present rank from his entry date. You'll see some entry dates and SVC are the same. Some get their commissions right out of college or officer candidate school. On the other hand, an entry date of a 1 LT in 1968 and the SVC date 1970 means it took two years to make 1 LT from 2 LT. Therefore, the SVC is a current date. Officer ranks in the army go from 2 LT (2nd Lieutenant), 1 LT (1st Lieutenant), CPT (Captain), MJR (Major), etc. Some are listed as CWO which is a rank between enlisted and officer.
Proud to say our daughter is a presently a new 2 LT in the Army National Guard. Maybe I should ask her about this one!
I think we need a ruling from Anna on this; however. There's a lot of confusion and we need an official answer. (I do think that it's important to note that some SVC and entry dates are the same)!