nonamethanks said:
Any reason to have the number here? Are there any conflicts between series? Otherwise we typically don't add the series number to qualifiers.
Technically the other way would be fine too as IIDX is basically synonymous with Beatmania as the other two were very shortlived while IIDX is a long-running and successful series.
I only suggested it this way because it seemed like most of the tags were *_(beatmania_iidx). I actually prefer *_(beatmania) though, Beatmania and Beatmania III literally do not have characters.