Maybe the terminology was different back then, but I'm pretty sure he got his early release from active duty (a lot of officers got that back then as there were a ton of them clogging up the officer lists at the junior level) and then went into what we call the Individual Ready Reserve, which is different from the Selected Reserve.
The IRR has no drill requirements, and the Selected Reserve (SELRES) has 11 drill weekends a year. In a drill weekend, you have four 4-hour periods, each counting for a drill day, for which the member receives a full day's pay.
In order to get a "good year", you need those 4 hour periods, which convert into points, and you also have to have an officer correspondence course or two, PLUS 2 weeks of ACDUTRA - active duty for training. Even then, failure to make a "good year" only causes an extension of a further year in the SELRES, barring permission to make up those points or an excusal by the Chief of Naval Reserve Personnel(CNAVRESPERS).
Kerry would have had to totally blow off every drill period for any time that he was obligated in the SELRES and then refused all chances at regaining points, in order for him to have his ultimate Discharge Certificate reflect a General classification. Not impossible, but there would have been a papertrail from his reserve unit Commanding Officer, much like Bush had all those reams of reserve paperwork following him around.
Like I said, I don't think he was ever in the SELRES. If he got a General, it was for the reasons I stated earlier.
I don't know. I just took the terminology right from his records. What few there are. :) And the explanation regarding the reserve requirement of 48 drills is on his contract.