R.A.B.'s identity confirmed?

[hickengruendler]

No: HPFGUIDX 139094

Hickengruendler:

The Harry Potter Lexicon claimed, that a trustworthy source has 
confirmed to them, that R.A.B. is indeed Regulus Black, and that his 
middle name is Arcturus. (Which would make the translation of Regulus' 
first and middle name "King Arthur".)

See here for more informations: http://www.hp-
lexicon.org/wizards/regulus.html

I want to add that the Lexicon normally is a very trustworthy source, 
and that I'm sure they wouldn't put any speculation as a fact, if they 
hadn't a really good reason to do so. Therefore IMO this information is 
likely to be true, even we can't be 100% certain right now.

Hickengruendler