Looking at Christine's link which has a good explanation of what the A.G. means (thanks C! :kissy:) I also noticed in the other abbreviations that those for Czech companies show A.S.
the Czech Republic (AkciovÃ¡ společnost, a.s.)
so, as Inwald started out as a Czech company, would the A.S. be correct up until the time the headquarters moved to Vienna and became a joint stock company? (i.e. 1908, two years after the death of Josef Inwald himself.) [Sources: Neue Deutsche Biographie.] Or was it post-1908 and aimed at the Czech market rather than the German one? Or there might be some other reason... Glen, it is interesting as you say, does your catalogue date (or appear to date) to before 1908?