and i got some question about his work listwhat do those little letters after the numbers mean
Theyare denoted works found later. For example, K45 and K46 had been datedfirst, but new pieces of works were found later and dated in betweenthem; thus "K45a" and "K45b" were used reasonably and conveniently tokeep track of this historical process.
You might ask what ifpeople find a new piece and date it between K45 and K45a. Well...That's why his work list has so many different versions. In recent50-100 years, I believe, canonical versions were well published andthere shouldn't be any incompatibility and confusion. Musicologists,compared to researchers in other fields, do talk to each other. : )