conventions are organised by volunteers and have had no formal support. If volunteers want to create a convention during their countries spring/summer than there is no rule stating they can not.
There is no such rule, but it would probably not be fair to call it the International BC Anniversary Convention, seeing as it doesn't happen around the anniversary.
Fair enough about the terminology. I thought the event was called the International Bookcrossing convention, and all other organised events were Uncons or meetups.
I believe at this point insisting it has to happen in a certain month is beginning to border on strange, the international conventions are a voluntary spin off of this site.