> Indeed, it is not exactly said and should be added in the API 
> documentation, but because the API documentation is not a wiki, I cannot 
> do that, and neither can you. However, the "Making plugins" page of the 
> wiki does contain this sentence: "This is usually done After_rules." in 
> the "Manage tags" part. It is true that it does not mention explicitely 
> the "flag" function, but along with the examples it should be clear 
> enough. Isn't it?

Sorry, I answered too fast: "flag" is really different than "tag", so my 
answer is kind of silly here ;) However, there ARE some examples in the 
part which talks about "flag", where we clearly see an usage (After_rules).

-- 
Romain Bardou