Hmmm, let me try another attempt ...
I alwayws thought the regular J-10 in PLAAF-service is the "A" version ... but was always curious why the trainer was "only" called the S-version, as it seemed as if - following some reports - the initial model / prototype version powered by the originla WS-10 (nut the current WS-10A) was called only J-10 but now that makes much more sense to me. All previous (at least the prototypes, pre-prod. aircarfts and block 01-03 should be called J-10 and their trainers respectively J-10S.
Regarding the A-model operational "now" with the first division ... I think/guess this "now" is already some time ago and - IMO if I'm not completely wrong - could refer to the first sighttings of the updated models with SATNAV/GPS-dome behind the cockpit and IFR-capability ....
Maybe (just let me guess) previous delivered models esp. the ones at the 44. Division were then updated with this latest stuff and should now be something like J-10+ and J-10S+ ... and new delivered examples are J-10A and J-10AS.
Deino