Why Nokia called Symbian Anna, Symbian Belle?
I don't think that there are any official annoucements on anything called Belle, thus, I would not expect anybody confirming that.
anyway, Why are you asking ?
All and all, Anna, Belle, C... sounds pretty logical..
There is an official announcement on Belle: http://press.nokia.com/2011/08/24/no...symbian-belle/
Anyway, there's was Symbian OS v9.4... Then Nokia bought the rest of Symbian Ltd, created Symbian Foundation and renamed the last version to Symbian^1 as a package with S60 5h Edition (i.e., Symbian 9.4 + S60 5th Edition was collectively named as Symbian^1). It was then also decided that v9.5, v10, etc., wouldn't be called that. Then came Symbian^2, a partially open source version. Then came Symbian^3 as the fully open source version, and Symbian Foundation's next release was to be Symbian^4.
Then Nokia decided that it'd (more or less) close Symbian Foundation and said it'd stop using version numbers, and just call the thing "Symbian".
Then they realized that it makes no sense as it'd be too hard to know what you're talking about, if the product still evolves. So, some marketeer or a committé decided that instead of version numbers they'd use cute alphabetic names (Anna, Belle, C...).
So, answer to "why" is: Because.
that announcement was many hours after my posts, it does not matter whether it i 15 minutes earlier or 15 months earlier, basically without official announcements anything discussed is not official.
I think it is just version number replacing numeric value